Domain Name System: Wikis

  
  
  

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.The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network.^ DNS An acronym that can stand for both Domain Name System and Domain Name Service.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ Domain name system explained.
  • Learn about Domain name registrations, renewals and transfers. Domain name system explained. 19 January 2010 9:54 UTC www.anchor.com.au [Source type: Reference]

^ NS_DNS The Domain Name System used in the Internet for host name resolution.
  • Amazon.com: "The Domain Name System": Key Phrase page 19 January 2010 9:54 UTC www.amazon.com [Source type: General]

.It associates various information with domain names assigned to each of the participants.^ It associates various information with the domain names assigned to each of the participants.
  • http://getglue.com/topics/p/domain_name_system 19 January 2010 9:54 UTC getglue.com [Source type: FILTERED WITH BAYES]

^ This information is required for domain name registration.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ What information is collected when registering a domain name?
  • Domain Names 19 January 2010 9:54 UTC www.cippic.ca [Source type: Reference]

.Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.^ DNS servers translate these domain names into...
  • domain names Resources | ZDNet 19 January 2010 9:54 UTC updates.zdnet.com [Source type: General]

^ An MX record associates the domain name to a domain name classified in an address record (A record).
  • Name resolution and Domain Name System in a Microsoft TCP/IP-based network | uCertify Articles 19 January 2010 9:54 UTC www.ucertify.com [Source type: Reference]

^ These are the most common of the domain name subheadings.
  • Free DNS Tutorial - Provided by Laynetworks.com 19 January 2010 9:54 UTC laynetworks.com [Source type: FILTERED WITH BAYES]

.An often used analogy to explain the Domain Name System is that it serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses.^ WhoIs An Internet Utility that returns information about a domain name or IP address.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ DNS is what's responsible for translating domain names in IP addresses - this process is called resolving.
  • Triple.com - Articles: DNS (Domain Name System) History 19 January 2010 9:54 UTC www.triple.com [Source type: General]

^ DNS servers translate these domain names into...
  • domain names Resources | ZDNet 19 January 2010 9:54 UTC updates.zdnet.com [Source type: General]

.For example, www.example.com translates to 192.0.32.10.^ IN      MX      10 galaxy.example.com.
  • Linux Home Server HOWTO - Domain Name System (BIND) 19 January 2010 9:54 UTC www.brennan.id.au [Source type: General]

^ For example, the domain name www.qualitylinkbuilding.com www.seo-professional-india.com www.mcsweb.in www.onlinecreditcardsinfo.com www.ebooks-sale-ebooks-buyer.com might translate to 198.105.232.4.
  • Domain Names - Web Hosting - Databases - Domain Name 19 January 2010 9:54 UTC selldomaindomain.com [Source type: General]

^ Let us take, for example, 'www.mapname.com'.
  • Frequently Asked Questions about Domain Names 19 January 2010 9:54 UTC mapname.com [Source type: General]

.The Domain Name System makes it possible to assign domain names to groups of Internet users in a meaningful way, independent of each user's physical location.^ Extending the domain name system .
  • it.gen.nz » Extending the domain name system 19 January 2010 9:54 UTC it.gen.nz [Source type: General]

^ NS_DNS The Domain Name System used in the Internet for host name resolution.
  • Amazon.com: "The Domain Name System": Key Phrase page 19 January 2010 9:54 UTC www.amazon.com [Source type: General]

^ Domain Name A domain name is essentially a signpost on the Internet.
  • DomainProcessor.com - Domain Name Registration Service 19 January 2010 9:54 UTC www.domainprocessor.com [Source type: FILTERED WITH BAYES]

.Because of this, World Wide Web (WWW) hyperlinks and Internet contact information can remain consistent and constant even if the current Internet routing arrangements change or the participant uses a mobile device.^ How can I change the information in the Contacts later?
  • cheap domain name registration & domain hosting service 19 January 2010 9:54 UTC www.netlynx.com [Source type: General]

^ Browser Software used to search and retrieve information from the World Wide Web.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ This kind of shift will require an adjustment to the routing information used by the Internet.
  • Things to do to protect the Domain Name System 19 January 2010 9:54 UTC www.cavebear.com [Source type: Original source]

.Internet domain names are easier to remember than IP addresses such as 208.77.188.166 (IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6).^ WhoIs An Internet Utility that returns information about a domain name or IP address.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ The domain name is mapped to an Internet Protocol (IP) address (which represents a physical point on the Internet).
  • HHS Policy for Internet Domain Names 19 January 2010 9:54 UTC www.hhs.gov [Source type: FILTERED WITH BAYES]

^ Internet domain names are easier to remember than IP addresses such as 208.77.188.166 (IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6).
  • http://getglue.com/topics/p/domain_name_system 19 January 2010 9:54 UTC getglue.com [Source type: FILTERED WITH BAYES]
  • Domain Name System, Technological Concept - News - Evri 19 January 2010 9:54 UTC www.evri.com [Source type: FILTERED WITH BAYES]

.People take advantage of this when they recite meaningful URLs and e-mail addresses without having to know how the machine will actually locate them.^ People take advantage of this when they recite meaningful URLs and e-mail addresses without having to know how the machine will actually locate them.
  • Domain Name System, Technological Concept - News - Evri 19 January 2010 9:54 UTC www.evri.com [Source type: FILTERED WITH BAYES]

^ People take advantage of this when they recite meaningful URLs and e-mail addresses without caring how the machine will actually locate them.
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

^ Well, these are becoming increasingly important simply because there are so many people in the world who try to take advantage of the open system that is the Internet.
  • Domain Name System (DNS) Simplified | Copier Catalog 19 January 2010 9:54 UTC www.copiercatalog.com [Source type: General]

.The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain.^ Address, or "A" records, map the name of a machine to its numeric IP address.
  • DNS, Domain Name System - SafeDNS FAQs 19 January 2010 18:018 UTC www.safedns.co.uk [Source type: General]

^ Domain Name registrations and Name Servers Registration .
  • Domain Name registrations and Name Servers Registration 19 January 2010 9:54 UTC www.hostitwise.com [Source type: Reference]

^ The domain name is mapped to an Internet Protocol (IP) address (which represents a physical point on the Internet).
  • HHS Policy for Internet Domain Names 19 January 2010 9:54 UTC www.hhs.gov [Source type: FILTERED WITH BAYES]

.Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains.^ The .com server, in turn, refers to the authoritative server for the company2.com domain.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ Responses to “Domain Names 101” .
  • Domain Names 101 : Small Business Support Network 19 January 2010 9:54 UTC www.ozsmallbiz.net [Source type: General]

^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

.This mechanism has made the DNS distributed, fault tolerant, and helped avoid the need for a single central register to be continually consulted and updated.^ This mechanism has made the DNS distributed, fault tolerant, and helped avoid the need for a single central register to be continually consulted and updated.
  • Domain Name System, Technological Concept - News - Evri 19 January 2010 9:54 UTC www.evri.com [Source type: FILTERED WITH BAYES]

^ Alternatively a single hostname may correspond to many IP addresses: this can facilitate fault tolerance and load distribution, and also allows a site to move physical location seamlessly.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ DNS Fault Tolerance Due to their critical role in supporting Internet connectivity, DNS servers can be configured in a fault-tolerant fashion.
  • Domain Name System - Hill2dot0 19 January 2010 9:54 UTC www.hill2dot0.com [Source type: Reference]

.In general, the Domain Name System also stores other types of information, such as the list of mail servers that accept email for a given Internet domain.^ Domain name wait-list .
  • The Domain Name System (DNS) and Administering the root ccTLD .ph | BerneGuerrero.com 19 January 2010 9:54 UTC berneguerrero.com [Source type: FILTERED WITH BAYES]

^ Name server list.
  • Registering, Managing, & Cancelling Domain Names 19 January 2010 18:018 UTC dnc.org.nz [Source type: FILTERED WITH BAYES]

^ It is very much a domain name system (DNS) type of model.
  • What Would a Grid Domain Name System Look Like? | Architecture - InfoWorld 19 January 2010 9:54 UTC www.infoworld.com [Source type: General]

.By providing a worldwide, distributed keyword-based redirection service, the Domain Name System is an essential component of the functionality of the Internet.^ DNS An acronym that can stand for both Domain Name System and Domain Name Service.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ Domain name service is an Internet service that translates domain names into IP addresses.
  • DNS Server Overview - Introduction to Domain Name System 19 January 2010 18:018 UTC www.networktutorials.info [Source type: FILTERED WITH BAYES]

^ Internet directory based upon names related to domain names .
  • Internet domain name registration system - Google Patent Search 19 January 2010 9:54 UTC www.google.com [Source type: Reference]

Other identifiers such as RFID tags, UPC codes, International characters in email addresses and host names, and a variety of other identifiers could all potentially utilize DNS.[1]
.The Domain Name System also defines the technical underpinnings of the functionality of this database service.^ DNS An acronym that can stand for both Domain Name System and Domain Name Service.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ Extending the domain name system .
  • it.gen.nz » Extending the domain name system 19 January 2010 9:54 UTC it.gen.nz [Source type: General]

^ Domain Name System (DNS) suffix.
  • DNS (Domain Name System) 19 January 2010 9:54 UTC www.computing.net [Source type: FILTERED WITH BAYES]

.For this purpose it defines the DNS protocol, a detailed specification of the data structures and communication exchanges used in DNS, as part of the Internet Protocol Suite (TCP/IP).^ The DNS is a widely used naming service on the Internet and other TCP/IP networks.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Governance of the DNS is part, but not all, of governing the Internet.
  • Signposts in Cyberspace: The Domain Name System and Internet Navigation 19 January 2010 9:54 UTC www.nap.edu [Source type: FILTERED WITH BAYES]

^ The Internet uses the numeric IP address to send data.
  • What Is a Domain Name? 19 January 2010 18:018 UTC www.freeservers.com [Source type: FILTERED WITH BAYES]

The Internet Protocol Suite
Application Layer
BGP · DHCP · DNS · FTP · GTP · HTTP · IMAP · IRC · Megaco · MGCP · NNTP · NTP · POP · RIP · RPC · RTP · RTSP · SDP · SIP · SMTP · SNMP · SOAP · SSH · Telnet · TLS/SSL · XMPP · (more)
Transport Layer
TCP · UDP · DCCP · SCTP · RSVP · ECN · OSPF · (more)
Internet Layer
IP (IPv4, IPv6) · ICMP · ICMPv6 · IGMP · IPsec · (more)
Link Layer
ARP/InARP · NDP · Tunnels (L2TP) · PPP · Media Access Control (Ethernet, DSL, ISDN, FDDI) · (more)

Contents

Overview

.The Internet maintains two principal namespaces, the domain name hierarchy[2] and the Internet Protocol (IP) address system.^ WhoIs An Internet Utility that returns information about a domain name or IP address.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ R esolve The process by which domain names are matched with corresponding Internet Protocol (IP) numbers.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

^ In the new domain style name system this property must be maintained.
  • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]
  • RFC 897 (rfc897) - Domain name system implementation schedule 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

[3] .The Domain Name System maintains the domain namespace and provides translation services between these two namespaces.^ (NSI) for some of these services, including the domain name registration services.
  • Government Domain Name Policy 19 January 2010 18:018 UTC www.choicefree.com [Source type: FILTERED WITH BAYES]

^ DNS servers translate these domain names into...
  • domain names Resources | ZDNet 19 January 2010 9:54 UTC updates.zdnet.com [Source type: General]

^ In the new domain style name system this property must be maintained.
  • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]
  • RFC 897 (rfc897) - Domain name system implementation schedule 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

.Internet name servers and a communications protocol, implement the Domain Name System.^ Development of the domain name system .
  • Development of the domain name system 19 January 2010 9:54 UTC portal.acm.org [Source type: Academic]
  • Development of the domain name system 19 January 2010 9:54 UTC portal.acm.org [Source type: Academic]

^ A domain name server defines a zone, i.e.
  • DNS (Domain Name System) 19 January 2010 9:54 UTC en.kioskea.net [Source type: Reference]

^ RFC 921 - Domain name system implementation schedule - revised .
  • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

[4] .A DNS name server is a server that stores the DNS records, such as address (A) records, name server (NS) records, and mail exchanger (MX) records for a domain name (see also List of DNS record types) and responds with answers to queries against its database.^ Domain name wait-list .
  • The Domain Name System (DNS) and Administering the root ccTLD .ph | BerneGuerrero.com 19 January 2010 9:54 UTC berneguerrero.com [Source type: FILTERED WITH BAYES]

^ Name server list.
  • Registering, Managing, & Cancelling Domain Names 19 January 2010 18:018 UTC dnc.org.nz [Source type: FILTERED WITH BAYES]

^ Type: MX - mail exchanger is used with DNS to denote the correct type of name resolution.
  • Lesson 13: Domain Name System (DNS) 19 January 2010 9:54 UTC www.cis.njit.edu [Source type: Reference]

History

.The practice of using a name as a humanly more meaningful abstraction of a host's numerical address on the network dates back to the ARPANET era.^ When using host tables, address-to-name mapping is trivial.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Host name to host address translation.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ If you are on a network that has a domain name, use that domain name.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

.Before the DNS was invented in 1983, each computer on the network retrieved a file called HOSTS.TXT from a computer at SRI (now SRI International).^ With the older system, each computer on the network retrieved a file called HOSTS.TXT from a computer at SRI (now SRI International).
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

^ In sum, the DNS is a network of computers, data files, software, and people.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ Originally, each computer on the network retrieved a file called HOSTS.TXT from SRI (now SRI International) which mapped an address (ex.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

[5][6] .The HOSTS.TXT file mapped names to numerical addresses.^ Address, or "A" records, map the name of a machine to its numeric IP address.
  • DNS, Domain Name System - SafeDNS FAQs 19 January 2010 18:018 UTC www.safedns.co.uk [Source type: General]

^ When using host tables, address-to-name mapping is trivial.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Enter a web address ,a host name or any name: e.g.
  • domain names Resources | ZDNet 19 January 2010 9:54 UTC updates.zdnet.com [Source type: General]

.A hosts file still exists on most modern operating systems, either by default or through explicit configuration.^ These are the default DNS configuration files.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ The Hosts file still exists on most modern operating systems either by default or through configuration and allows users to specify an IP Address to use for a hostname without checking the DNS. This file is now used primarily for troubleshooting DNS errors or mapping local addresses to more organic names.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ When a host is configured, manually or through DHCP, it's assigned at least one default name server along with its IP address and subnet mask.

.Many operating systems use name resolution logic that allows the administrator to configure selection priorities for available DNS resolution methods.^ Name resolution in DNS .

^ The DNS operates on the basis of a hierarchy of names.
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ This is a detailed guide to the Domain Name System, its implementation, configuration, and administration.
  • DNS in Action 19 January 2010 18:018 UTC www.packtpub.com [Source type: General]

.The rapid growth of the network required a scalable system that recorded a change in a host's address in one place only.^ There's only one A record for each host.
  • SamSpade.org 19 January 2010 18:018 UTC samspade.org [Source type: General]

^ Address records for hosts / network equipment .
  • Linux Home Server HOWTO - Domain Name System (BIND) 19 January 2010 9:54 UTC www.brennan.id.au [Source type: General]

^ The growth of networking called for a more scalable system: one that recorded a change in a host's address in one place only.
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

.Other hosts would learn about the change dynamically through a notification system, thus completing a globally accessible network of all hosts' names and their associated IP addresses.^ Learn about Domain Names .

^ Through this procedure, the DNS translates names to IP addresses.
  • Domain Name System 19 January 2010 9:54 UTC www.javabeat.net [Source type: FILTERED WITH BAYES]

^ Learn more about a domain name.
  • Domain Names 19 January 2010 9:54 UTC www.buzzle.com [Source type: General]

.At the request of Jon Postel, Paul Mockapetris invented the Domain Name System in 1983 and wrote the first implementation.^ Domain Name System (DNS) suffix.
  • DNS (Domain Name System) 19 January 2010 9:54 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ Development of the domain name system .
  • Development of the domain name system 19 January 2010 9:54 UTC portal.acm.org [Source type: Academic]
  • Development of the domain name system 19 January 2010 9:54 UTC portal.acm.org [Source type: Academic]

^ RFC 921 - Domain name system implementation schedule - revised .
  • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

.The original specifications appeared in RFC 882 and RFC 883 which were superseded in November 1987 by RFC 1034[2] and RFC 1035.^ Obsoletes: RFC 882 , RFC 883 , RFC 973 .
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ In 1987, the publication of RFC 1034 and RFC 1035 updated the DNS specification and made RFC 882 and RFC 883 obsolete.
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ Updates: RFC 1034 , RFC 1035 .
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

[4] .Several additional Request for Comments have proposed various extensions to the core DNS protocols.^ Several more recent RFCs have proposed various extensions to the core DNS protocols.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ The primary specifications for DNS are defined in Requests for Comments (RFC) 1034 and 1035.
  • Domain Name System (DNS) – Part I Name Resolution | NetworkWorld.com Community 19 January 2010 18:018 UTC www.networkworld.com [Source type: Reference]

^ In addition to forwarding DNS requests and the recursive nature, you can also configure more than one server to be 'authoritative' for a particular domain.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.In 1984, four Berkeley students—Douglas Terry, Mark Painter, David Riggle and Songnian Zhou—wrote the first UNIX implementation, which was maintained by Ralph Campbell thereafter.^ In 1984, four Berkeley students — Douglas Terry, Mark Painter, David Riggle and Songnian Zhou — wrote the first UNIX implementation, which was maintained by Ralph Campbell thereafter.
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

^ In 1985, Kevin Dunlap of DEC significantly re-wrote the DNS implementation and renamed it BIND (Berkeley Internet Name Domain, previously: Berkeley Internet Name Daemon).
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

^ The most popular implementation of the DNS protocol is the Berkeley Internet Name Domain (BIND), which was developed for the UC Berkeley’s BSD UNIX operating system.
  • Domain Name System (DNS) – Part I Name Resolution | NetworkWorld.com Community 19 January 2010 18:018 UTC www.networkworld.com [Source type: Reference]

.In 1985, Kevin Dunlap of DEC significantly re-wrote the DNS implementation and renamed it BIND—Berkeley Internet Name Domain.^ Domain Name System (DNS) suffix.
  • DNS (Domain Name System) 19 January 2010 9:54 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ The domain name vs. Internet.
  • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

^ Web Ten includes a complete implementation of the Berkeley Internet Named Domain (BIND) DNS, version 8.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

.Mike Karels, Phil Almquist and Paul Vixie have maintained BIND since then.^ Mike Karels, Phil Almquist and Paul Vixie have maintained BIND since then.
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

.BIND was ported to the Windows NT platform in the early 1990s.^ BIND was ported to the Windows NT platform in the early 1990s.
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

.BIND was widely distributed, especially on Unix systems, and is the dominant DNS software in use on the Internet.^ American Registry for Internet Numbers (ARIN) Internet Corporation for Assigned Names and Numbers (ICANN) www.DNSstuff.com (useful DNS tools) Books: .
  • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

^ In the next article we will take a high-level look at the Bind 9 DNS server software typically used on Linux and Unix name servers and the basis of most DNS server implementations used on the Internet.
  • Running Your Own DNS Server: Understanding the Domain Name System 19 January 2010 9:54 UTC services.communitymx.com [Source type: FILTERED WITH BAYES]

^ In 1985, Kevin Dunlap of DEC significantly re-wrote the DNS implementation and renamed it BIND (Berkeley Internet Name Domain, previously: Berkeley Internet Name Daemon).
  • Domain Name Systems | Nicolae Sfetcu 19 January 2010 9:54 UTC www.sfetcu.com [Source type: General]

[7] .With the heavy use and resulting scrutiny of its open-source code, as well as increasingly more sophisticated attack methods, many security flaws were discovered in BIND. This contributed to the development of a number of alternative nameserver and resolver programs.^ Reselling Domain Names Features of domain name reseller programs - Reselling domain names provides an additional service to attract and keep clients as well as another source of recurring revenue.
  • Domain Names 19 January 2010 9:54 UTC www.buzzle.com [Source type: General]

^ Well, these are becoming increasingly important simply because there are so many people in the world who try to take advantage of the open system that is the Internet.
  • Domain Name System (DNS) Simplified | Copier Catalog 19 January 2010 9:54 UTC www.copiercatalog.com [Source type: General]

^ It then returns its results to the DNS resolver; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

.BIND itself was re-written from scratch in version 9, which has a security record comparable to other modern Internet software.^ The Berkley Internet Name Domain (BIND) software provides a server daemon called named that answers requests for information about the IP address assigned to a symbolic name (or a reverse lookup, or other information).
  • TUTORIAL FOR LPI EXAM 202: part 3 -- Topic 207: Domain Name System (DNS) -- 19 January 2010 9:54 UTC gnosis.cx [Source type: Reference]

^ LCD TV PlayStation 3 Printer reviews Security software Wii Windows Vista CNET sites CNET Site map CNET TV Downloads News Reviews Shopper.com Other CNET sites .
  • ICANN needs to clamp down on domain name abuse - CNET News 19 January 2010 9:54 UTC news.cnet.com [Source type: General]

^ This document reports the conclusions of an assessment of the current state and the future prospects of the DNS and its interactions with Internet navigation, including its uses as a means of navigation itself and as an infrastructure for navigation by other means.
  • Signposts in Cyberspace: The Domain Name System and Internet Navigation 19 January 2010 9:54 UTC www.nap.edu [Source type: FILTERED WITH BAYES]

.The DNS protocol was developed and defined in the early 1980s and published by the Internet Engineering Task Force.^ NSI has asked the Internet Engineering Task Force to publish RRP as an informational document.
  • CNN - Is domain name system vulnerable to slamming? - January 18, 2000 19 January 2010 9:54 UTC archives.cnn.com [Source type: General]

^ When the Internet was being collaboratively developed by a substantially technical community around a growing but still manageable Internet Engineering Task Force, the Domain Name System (DNS) evolved as a hierarchical solution to the problem of keeping track of which computers had which Internet Protocol (IP) addresses.
  • Domain Names - Web Hosting - Databases - Domain Name 19 January 2010 9:54 UTC selldomaindomain.com [Source type: General]

^ Insecure underlying protocols and lack of authentication and integrity checking of the information within the DNS threaten the proper functionality of the DNS. The Internet Engineering Task Force (IETF) is working on DNS security extensions to increase security within the DNS, known as DNSSEC. These security issues and solutions are presented in this paper.

Structure

The domain name space

The hierarchical domain name system, organized into zones, each served by a name server.
.The domain name space consists of a tree of domain names.^ Each node on the tree is a partition of the name space called a domain.
  • Domain Name System (DNS) – Part I Name Resolution | NetworkWorld.com Community 19 January 2010 18:018 UTC www.networkworld.com [Source type: Reference]

^ Example of inverse domains and the Domain Name Space .

^ A domain is identified by a domain name, and consists of that part of the domain name space that is at or below the domain name which specifies the domain.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.Each node or leaf in the tree has zero or more resource records, which hold information associated with the domain name.^ It associates various information with the domain names assigned to each of the participants.
  • http://getglue.com/topics/p/domain_name_system 19 January 2010 9:54 UTC getglue.com [Source type: FILTERED WITH BAYES]

^ Resource Records The data associated with domain names are contained in resource records , or RR s .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Learn more about a domain name.
  • Domain Names 19 January 2010 9:54 UTC www.buzzle.com [Source type: General]

.The tree sub-divides into zones beginning at the root zone.^ How the database is divided into zones The domain database is partitioned in two ways: by class, and by "cuts" made in the name space between nodes.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ The database is divided up into sections called zones, which are distributed among the name servers.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Given, the tree structure, every zone has a highest node which is closer to the root than any other node in the zone.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.A DNS zone consists of a collection of connected nodes authoritatively served by an authoritative nameserver.^ A DNS server can be authoritative for several zones.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ DNS servers that store Resource Records for a zone, whether they be primary or secondary servers, are said to be authoritative for the zone.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ If you want a server to authoritatively serve zone data, but don't want it to be the location from which you make zone modifications, then it is a perfect candidate to be a slave server.
  • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

.(Note that a single nameserver can host several zones.^ A single zone can either be a forward zone (i.e., zone information that pertains to a given domain) or an inverse zone (i.e., zone information that maps IP addresses into DNS host names).

^ Sophisticated DNS features include the mapping of several different names to a single Internet address and the mapping of several different Internet addresses to a single host name.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Note that there is no requirement that the servers for a zone reside in a host which has a name in that domain.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

)
.Administrative responsibility over any zone may be divided, thereby creating additional zones.^ The method is that a name server may add an SOA RR to the additional section of a response when that response is authoritative.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Different branches of this tree may belong to different administrative entities, and each branch can further delegate responsibility.
  • CFP WFPD: Replacing the Domain Name System 19 January 2010 18:018 UTC www.cfp2000.org [Source type: Original source]

^ System Administration Toolkit: Time and event management (Martin Brown, developerWorks, May 2006) covers the creation and organization of time scripts using cron and at.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.Authority is said to be delegated for a portion of the old space, usually in form of sub-domains, to another nameserver and administrative entity.^ Domains are administrative entities.
  • ISC-TN-2004-2: The role of the Domain Name System in the development of new Internet services 19 January 2010 18:018 UTC ftp.isc.org [Source type: FILTERED WITH BAYES]

^ This nameserver is secondary for another domain.
  • Internet Domain Name Structure 19 January 2010 9:54 UTC www.aunic.net [Source type: Reference]

^ Since this can introduce a bootstrapping problem when the name of the nameserver is in the domain about which nothing is yet known, it is occasionally necessary for the nameserver providing the delegation to also provide the IP address of the next nameserver.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

.The old zone ceases to be authoritative for the new zone.^ The time at which the zone becomes no longer authoritative and a new interrogation of the root servers is required.
  • How IT Works: Domain Name System 19 January 2010 9:54 UTC technet.microsoft.com [Source type: FILTERED WITH BAYES]

Domain name formulation

.The definitive descriptions of the rules for forming domain names appear in RFC 1035, RFC 1123, and RFC 2181.^ The specific conclusions and recommendations of the Committee on Internet Navigation and the Domain Name System appear throughout this summary in boldface type.
  • Signposts in Cyberspace: The Domain Name System and Internet Navigation 19 January 2010 9:54 UTC www.nap.edu [Source type: FILTERED WITH BAYES]

^ The mail system still uses addresses of the form "local-part@host", where host is a domain style host name.
  • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

^ C ontact Form (Contact Template) The electronic form used to register a new domain name contact/agent or modify information for an existing contact.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

.A domain name consists of one or more parts, technically called labels, that are conventionally concatenated, and delimited by dots, such as example.com.^ The dots divide domain names into different parts.
  • The Internet Domain Name System Explained for Non-Experts - ISOC Member Briefing #16 19 January 2010 9:54 UTC www.isoc.org [Source type: Original source]

^ For example, the host named bob.company.com consists of a host named bob inside a subdomain called company, which is a subdomain of the domain com.
  • Domain Name System 19 January 2010 9:54 UTC www.javabeat.net [Source type: FILTERED WITH BAYES]

^ For a domain name, which one would be better: .
  • Expired Domain Names 19 January 2010 9:54 UTC www.bizmint.com [Source type: General]

.
  • The right-most label conveys the top-level domain; for example, the domain name www.example.com belongs to the top-level domain com.
  • The hierarchy of domains descends from right to left; each label to the left specifies a subdivision, or subdomain of the domain to the right.^ Typically in an FQDN, the left most label is the host name, while the next label to the right is the local domain to which the host belongs.

    ^ In the case of the domain name "www.yourdomain.net", the third level domain is "www."
    • Cheap Domain Names - Domain Registration - Glossary for CheapDomain.com 19 January 2010 9:54 UTC www.cheapdomain.com [Source type: Reference]

    ^ From our example, www.mcslp.com, the 'com' is example of a top-level domain (TLD) name that organizes the names by organizational or regional structure.
    • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

    .For example: the label example specifies a subdomain of the com domain, and www is a subdomain of example.com.^ IN CNAME www.example.com.
    • How IT Works: Domain Name System 19 January 2010 9:54 UTC technet.microsoft.com [Source type: FILTERED WITH BAYES]

    ^ Each label to the left specifies a subdivision or subdomain of the domain above it.
    • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

    ^ For example, the .com in www.mysite.com is the top level domain.
    • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

    .This tree of subdivisions may consist of 127 levels.
  • Each label may contain up to 63 characters.^ Labels must be 63 characters or less.
    • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

    ^ In theory, this subdivision can go down to 127 levels deep, and each label can contain up to 63 characters, as long as the whole domain name does not exceed a total length of 255 characters.
    • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

    ^ Levels within a domain name may contain only specific characters.
    • Domain Name Policy - Policies - University of Florida Web Administration 19 January 2010 9:54 UTC www.webadmin.ufl.edu [Source type: FILTERED WITH BAYES]

    .The full domain name may not exceed a total length of 253 characters.^ The domain name may also be listed for auction.
    • REF Sales Systems - Domain Registration Agreement 19 January 2010 18:018 UTC www.refsalessystems.com [Source type: Reference]

    ^ What are the valid characters for booking a Domain Name?
    • cheap domain name registration & domain hosting service 19 January 2010 9:54 UTC www.netlynx.com [Source type: General]

    ^ The full domain name in question.
    • Domain Name Guide - Site5Wiki 19 January 2010 9:54 UTC wiki.site5.com [Source type: General]

    [8] .In practice, some domain registries may have shorter limits.
  • DNS names may technically consist of any character representable in an octet (RFC 3696).^ National Domain Name Registry, et.
    • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

    ^ There are some limits on these names.
    • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

    ^ The domain name may also be listed for auction.
    • REF Sales Systems - Domain Registration Agreement 19 January 2010 18:018 UTC www.refsalessystems.com [Source type: Reference]

    .However, the allowed formulation of domain names in the DNS root zone, and most other subdomains, uses a preferred format and character set.^ If a subdomain of the domain isn't delegated away, however, the zone contains the domain names and data in the subdomain.
    • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

    ^ A domain name is always suspended for a set time, which can at the most be 1 year.
    • Safenames : Regulations - FI, FI, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: FILTERED WITH BAYES]

    ^ In the Domain Name System (DNS), the highest level of the hierarchy after the root.
    • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

    .The characters allowed in a label are a subset of the ASCII character set, and includes the characters a through z, A through Z, digits 0 through 9, and the hyphen.^ Internationalised domain names Domain names must use only a subset of ASCII characters, preventing many languages from representing their names and words natively.
    • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

    ^ They must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen.
    • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

    ^ Valid domain name characters include letters, numbers and hyphens.
    • Dyntex Hosting - Domain Name: Registration FAQ 19 January 2010 18:018 UTC www.dyntex.com [Source type: General]

    .This rule is known as the LDH rule (letters, digits, hyphen).^ They must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen.
    • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

    ^ Domain names must commence and end with a letter or a digit; interior characters of domain names may be letters, digits or the hyphen character; no other characters may be used; names are case insensitive.
    • Registering, Managing, & Cancelling Domain Names 19 January 2010 18:018 UTC dnc.org.nz [Source type: FILTERED WITH BAYES]

    ^ They must start with a letter, end with a letter or digit and have only letters or digits or hyphen as interior characters.
    • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

    .Domain names are interpreted in case-independent manner.^ Domain names are not case-sensitive.
    • Domain Name Basics: An Introduction - webreference.com 19 January 2010 9:54 UTC www.webreference.com [Source type: General]

    ^ In the case of the domain name "www.yourdomain.net", the third level domain is "www."
    • Cheap Domain Names - Domain Registration - Glossary for CheapDomain.com 19 January 2010 9:54 UTC www.cheapdomain.com [Source type: Reference]

    ^ In the UK One In A Million case, [9] the cybersquatters registered a lot of domain names incorporating famous UK trademarks and trade names.
    • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

    .Labels may not start or end with a hyphen, nor may two hyphens occur in sequence.
  • A hostname is a domain name that has at least one IP address associated.^ Domain name A domain name is a Web address.
    • Cheap Domain Names - Domain Registration - Glossary for CheapDomain.com 19 January 2010 9:54 UTC www.cheapdomain.com [Source type: Reference]

    ^ Domain style names may have more than two segments.
    • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

    ^ Alias One of several alternative hostnames with the same IP address.
    • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

    For example, the domain names www.example.com and example.com are also hostnames, whereas the com domain is not.

Internationalized domain names

.The permitted character set of the DNS prevented the representation of names and words of many languages in their native alphabets or scripts.^ Internationalised domain names Domain names must use only a subset of ASCII characters, preventing many languages from representing their names and words natively.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ The birth of the Internet and the use of character strings (domain names) to represent Internet addresses has presented trademark owners with a whole new set of problems.
  • Case of Reverse Domain Name Hijacking Turns Against Unicom Systems -- Chilling Effects Clearinghouse 19 January 2010 18:018 UTC www.chillingeffects.org [Source type: FILTERED WITH BAYES]

^ Internationalized Domain Names (IDN) With our Internationalized Domain Names search capabilities, you can register .COM and .NET domain names in over 100 native languages (non-ASCII characters) such as Chinese, Japanese and Arabic.
  • WebDevel.com Domain Name Search - Search and Register Web Domain Names 19 January 2010 9:54 UTC webdevel.com [Source type: General]
  • HostEtc.com Domain Name Search - Search and Register Web Domain Names 19 January 2010 18:018 UTC hostetc.com [Source type: General]
  • Open Domain Names - Web Site Name Search Tool 19 January 2010 18:018 UTC opendomainnames.com [Source type: General]
  • Go Daddy Domain Name Search Tool 19 January 2010 18:018 UTC www.godaddy.com [Source type: General]

.ICANN has approved the Punycode-based Internationalized domain name (IDNA) system, which maps Unicode strings into the valid DNS character set.^ DNS servers translate these domain names into...
  • domain names Resources | ZDNet 19 January 2010 9:54 UTC updates.zdnet.com [Source type: General]

^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ Lesson 13: Domain Name System (DNS) Domain Name System (DNS) LESSON 13 .
  • Lesson 13: Domain Name System (DNS) 19 January 2010 9:54 UTC www.cis.njit.edu [Source type: Reference]

.In 2009 ICANN approved the installation of IDN county code top-level domains.^ PL is the country code Top-Level-Domain for Poland.
  • RRPproxy - Realtime Registration System for Reseller of domain names 19 January 2010 18:018 UTC en.rrpproxy.com [Source type: FILTERED WITH BAYES]

^ TW is the official country code Top-Level-Domain of Taiwan.
  • RRPproxy - Realtime Registration System for Reseller of domain names 19 January 2010 18:018 UTC en.rrpproxy.com [Source type: FILTERED WITH BAYES]

^ These are called country-code Top Level Domains, or ccTLDs.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

In addition, many registries of the existing TLDs have adopted IDNA.

Name servers

.The Domain Name System is maintained by a distributed database system, which uses the client-server model.^ A third level domain is controlled by the name servers used by a Registrant.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ In the new domain style name system this property must be maintained.
  • RFC 921 (rfc921) - Domain name system implementation schedule - revised 19 January 2010 9:54 UTC www.faqs.org [Source type: Reference]

^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

.The nodes of this database are the name servers.^ Changes you make to your name server's database can be picked up by the root servers in a few minutes or a few hours.
  • "PC-Unix Connection" The Domain Name System - Network Computing 19 January 2010 9:54 UTC www.networkcomputing.com [Source type: General]

^ Name servers contain information about some segment of the DNS database and make that information available to clients, called resolvers.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ How the database is divided into zones The domain database is partitioned in two ways: by class, and by "cuts" made in the name space between nodes.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.Each domain has at least one authoritative DNS server that publishes information about that domain and the name servers of any domains subordinate to it.^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ The DNS server which has direct access to the zone file with DNS information for a domain .
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ The Domain Information Groper is a DNS server interrogation tool.
  • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

.The top of the hierarchy is served by the root nameservers, the servers to query when looking up (resolving) a top-level domain name (TLD).^ A third level domain is controlled by the name servers used by a Registrant.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ The root server holds information on the top-level domains, but usually not on subdomains.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ Using the query domain name, QTYPE, and QCLASS, the name server looks for matching RRs.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

Authoritative name server

.An authoritative name server is a name server that gives answers that have been configured by an original source, for example, the domain administrator or by dynamic DNS methods, in contrast to answers that were obtained via a regular DNS query to another name server.^ Check with a network administrator to ensure that DNS servers are configured properly.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ No attempt is made to forward the query to another name server.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.An authoritative-only name server only returns answers to queries about domain names that have been specifically configured by the administrator.^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ This ensures that your slaves will return authoritative answers to queries for that domain.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ Because any one name server only knows about part of the overall domain name space, an inverse query is never guaranteed to return an answer.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.An authoritative name server can either be a master server or a slave server.^ Name servers can be authoritative for multiple zones, too.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ NS an authoritative name server .
  • Domain Name System (DNS) 19 January 2010 9:54 UTC www.freebsd.org [Source type: Reference]
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

^ An authoritative name server is needed when: .
  • Domain Name System (DNS) 19 January 2010 9:54 UTC www.freebsd.org [Source type: Reference]
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

.A master server is a server that stores the original (master) copies of all zone records.^ The name server uses the master files or copies to load its zones.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Master Servers of the existing Zone.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ A slave zone is a copy of a master zone stored on a slave or secondary name server.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

.A slave server uses an automatic updating mechanism of the DNS protocol in communication with its master to maintain an identical copy of the master records.^ Records for your server will automatically be created.
  • The default netbios domain name vishwanath0 was seleted due to name conflic 19 January 2010 18:018 UTC www.windowsbbs.com [Source type: General]

^ The name server uses the master files or copies to load its zones.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Slave zones use zone transfers to get copies of the master zone data.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

.Every DNS zone must be assigned a set of authoritative name servers that are installed in NS records in the parent zone.^ Setting up a DNS server .
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ A zone must have a primary server.
  • How IT Works: Domain Name System 19 January 2010 9:54 UTC technet.microsoft.com [Source type: FILTERED WITH BAYES]

.When domain names are registered with a domain name registrar their installation at the domain registry of a top level domain requires the assignment of a primary name server and at least one secondary name server.^ A third level domain is controlled by the name servers used by a Registrant.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ To register your Domain Name: .
  • Domain Names - Web Hosting - Databases - Domain Name 19 January 2010 9:54 UTC selldomaindomain.com [Source type: General]

^ One of the world wide top-level domain any person or organization may register a domain name.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

.The requirement of multiple name servers aims to make the domain still functional even if one name server becomes inaccessible or inoperable.^ DE names require a minimum of 2 name servers.
  • Domain Name Overview, Epping / Harlow, Essex, UK | Connex Hosting Limited 19 January 2010 9:54 UTC www.connexhosting.com [Source type: FILTERED WITH BAYES]

^ Each name server must be functioning.
  • Safenames : Regulations - FI, FI, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: FILTERED WITH BAYES]

^ Name servers can be authoritative for multiple zones, too.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

[9] .The designation of a primary name server is solely determined by the priority given to the domain name registrar.^ Can I change registrars after registering a domain name?
  • Domain Names - Web Hosting - Databases - Domain Name 19 January 2010 9:54 UTC selldomaindomain.com [Source type: General]

^ This DNS server is called the primary domain name server for the domain.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ A domains name server.
  • TUTORIAL FOR LPI EXAM 202: part 3 -- Topic 207: Domain Name System (DNS) -- 19 January 2010 9:54 UTC gnosis.cx [Source type: Reference]

.For this purpose generally only the fully qualified domain name of the name server is required, unless the servers are contained in the registered domain, in which case the corresponding IP address is needed as well.^ Domain name A domain name is a Web address.
  • Cheap Domain Names - Domain Registration - Glossary for CheapDomain.com 19 January 2010 9:54 UTC www.cheapdomain.com [Source type: Reference]

^ To register your Domain Name: .
  • Domain Names - Web Hosting - Databases - Domain Name 19 January 2010 9:54 UTC selldomaindomain.com [Source type: General]

^ P rimary Server The name server that will contain authoritative information for the domain name and will be used to resolve that domain name to its corresponding IP number(s).
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

.Primary name servers are often master name servers, while secondary name server may be implemented as slave servers.^ Calling a particular name server a primary master name server or a slave name server is a little imprecise, though.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Similarly, a name server can be a primary master for one zone and a slave for another.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Primary and secondary DNS servers .
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

.An authoritative server indicates its status of supplying definitive answers, deemed authoritative, by setting a software flag (a protocol structure bit), called the Authoritative Answer (AA) bit in its responses.^ When set to 1, identifies the response as one made by an authoritative name server.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ AA - Authoritative Answer 1-bit field.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ The header of the response looks like the header of the query, except that the RESPONSE bit is set, indicating that this message is a response, not a query, and the Authoritative Answer (AA) bit is set indicating that the address RRs in the answer section are from authoritative data.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

[4] This flag is usually reproduced prominently in the output of DNS administration query tools (such as dig) to indicate that the responding name server is an authority for the domain name in question.[4]

Recursive and caching name server

.In principle, authoritative name servers are sufficient for the operation of the Internet.^ In order for the internet to operate, name servers must be delegated as name servers.
  • Domain Name Systems - FAQS - Frequently asked questions 19 January 2010 9:54 UTC www.domainnamesystems.com [Source type: General]

^ Name servers can be authoritative for multiple zones, too.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ NS an authoritative name server .
  • Domain Name System (DNS) 19 January 2010 9:54 UTC www.freebsd.org [Source type: Reference]
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

.However, with only authoritative name servers operating, every DNS query must start with recursive queries at the root zone of the Domain Name System and each user system must implement resolver software capable of recursive operation.^ DNS An acronym that can stand for both Domain Name System and Domain Name Service.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ If set, the name server is directed to pursue the query recursively.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

.To improve efficiency, reduce DNS traffic across the Internet, and increase performance in end-user applications, the Domain Name System supports DNS cache servers which store DNS query results for a period of time determined in the configuration (time-to-live) of the domain name record in question.^ DNS An acronym that can stand for both Domain Name System and Domain Name Service.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ The time at which a domain name registration expires.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ The Internet Domain Name System (DNS) is a fascinating technology; almost all Internet applications make use of it.
  • The Internet Domain Name System Explained for Non-Experts - ISOC Member Briefing #16 19 January 2010 9:54 UTC www.isoc.org [Source type: Original source]

.Typically, such caching DNS servers, also called DNS caches, also implement the recursive algorithm necessary to resolve a given name starting with the DNS root through to the authoritative name servers of the queried domain.^ Name Server Also called a host (name server) r.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

^ If set, the name server is directed to pursue the query recursively.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

.With this function implemented in the name server, user applications gain efficiency in design and operation.^ Each name server must be functioning.
  • Safenames : Regulations - FI, FI, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: FILTERED WITH BAYES]

^ Creating a sub account will create a new user account with the same default contacts and default name servers.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ The user programs access name servers through standard programs called resolvers.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.The combination of DNS caching and recursive functions in a name server is not mandatory, the functions can be implemented independently in servers for special purposes.^ Each name server must be functioning.
  • Safenames : Regulations - FI, FI, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: FILTERED WITH BAYES]

^ A caching name server is a name server that is not authoritative for any zones.
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

^ All name servers must implement non-recursive queries.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.Internet service providers typically provide recursive and caching name servers for their customers.^ This provides for the service of transferring your name.
  • Domain Name Systems - FAQS - Frequently asked questions 19 January 2010 9:54 UTC www.domainnamesystems.com [Source type: General]

^ Many Internet Service Providers (ISPs) operate name server and provide their customers with name service when they register a domain name.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]
  • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

^ A caching name server is a name server that is not authoritative for any zones.
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

.In addition, many home networking routers implement DNS caches and recursors to improve efficiency in the local network.^ By caching DNS queries, the overall network demand is lowered considerably, especially on top level domain (TLD) servers.
  • TUTORIAL FOR LPI EXAM 202: part 3 -- Topic 207: Domain Name System (DNS) -- 19 January 2010 9:54 UTC gnosis.cx [Source type: Reference]

^ The other is to set up a DNS server on your local network.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ Kashpureff injected bogus information into DNS caches around the world concerning DNS information pertaining to Network Solutions Inc.’s (NSI) Internet’s Network Information Center (InterNIC).

DNS resolvers

.The client-side of the DNS is called a DNS resolver.^ For this reason, clients are often called resolvers.

^ On the client side of the DNS system, applications a resolver is a set of libraries that applications may utilize to communicating with DNS servers.
  • TUTORIAL FOR LPI EXAM 202: part 3 -- Topic 207: Domain Name System (DNS) -- 19 January 2010 9:54 UTC gnosis.cx [Source type: Reference]

^ The DNS specs call this kind of resolver a stub resolver .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.It is responsible for initiating and sequencing the queries that ultimately lead to a full resolution (translation) of the resource sought, e.g., translation of a domain name into an IP address.^ Account The person or company ultimately responsible for a domain name.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ How domain name resolution works .
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ Through this procedure, the DNS translates names to IP addresses.
  • Domain Name System 19 January 2010 9:54 UTC www.javabeat.net [Source type: FILTERED WITH BAYES]

A DNS query may be either a non-recursive query or a recursive query:
.
  • A non-recursive query is one in which the DNS server provides a record for a domain for which it is authoritative itself, or it provides a partial result without querying other servers.
  • A recursive query is one for which the DNS server will fully answer the query (or give an error) by querying other name servers as needed.^ The authoritative name servers must be updated when a change to the domain is made.
    • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

    ^ This ensures that your slaves will return authoritative answers to queries for that domain.
    • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

    ^ If it does not find that particular domain name, it refers the query to one of the root servers.
    • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

    DNS servers are not required to support recursive queries.
.The resolver, or another DNS server acting recursively on behalf of the resolver, negotiates use of recursive service using bits in the query headers.^ The name server that receives a query from a client can act on behalf of the client to resolve the query.

^ In the event of a negative answer, another DNS server is queried.
  • Articles & News: Domain Name Information - Domain-Names 19 January 2010 9:54 UTC articles.pointshop.com [Source type: General]

^ Because the resolver issued a recursive query.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.Resolving usually entails iterating through several name servers to find the needed information.^ An authoritative name server is needed when: .
  • Domain Name System (DNS) 19 January 2010 9:54 UTC www.freebsd.org [Source type: Reference]
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

^ A caching name server is needed when: .
  • Domain Name System (DNS) 19 January 2010 9:54 UTC www.freebsd.org [Source type: Reference]
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

^ An nslookup may also be used to find other types of information such as CNAME - the canonical name for an alias; MINFO - mailbox or mail list information; MX - mail exchanger information; NS - the name server for the named zone; and SOA the domain's start-of-authority information.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

.However, some resolvers function simplistically and can communicate only with a single name server.^ Each name server must be functioning.
  • Safenames : Regulations - FI, FI, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: FILTERED WITH BAYES]

^ Not all name servers do this, however.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ DNSSEC secures communication between domain name system (DNS) name servers and clients and helps protect against attacks such as cache poisoning.
  • domain name system - SC Magazine US 19 January 2010 9:54 UTC www.scmagazineus.com [Source type: General]

.These simple resolvers (called "stub resolvers") rely on a recursive name server to perform the work of finding information for them.^ Name Server Also called a host (name server) r.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

^ Name Server Also called a host (name server).
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

^ In recursion a resolver sends a recursive query to a name server for information about a particular domain name.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

Operation

Address resolution mechanism

.Domain name resolvers determine the appropriate domain name servers responsible for the domain name in question by a sequence of queries starting with the right-most (top-level) domain label.^ A third level domain is controlled by the name servers used by a Registrant.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

^ Explains the naming scheme for top level domains.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ The name server that receives a query from a client can act on behalf of the client to resolve the query.

A DNS recursor consults three nameservers to resolve the address www.wikipedia.org.
The process entails:
.
  1. A system that needs to use the DNS is configured with the known addresses of the root servers.^ Operation of the root server system.
    • Government Domain Name Policy 19 January 2010 18:018 UTC www.choicefree.com [Source type: FILTERED WITH BAYES]

    ^ DNS clients are configured with the addresses of DNS servers.
    • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

    ^ It then defines the root server information using the "."
    • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

    This is often stored in a file of root hints, which are updated periodically by an administrator from a reliable source.
  2. Query one of the root servers to find the server authoritative for the top-level domain.
  3. Query the obtained TLD DNS server for the address of a DNS server authoritative for the second-level domain.
  4. Repeating the previous step to process each domain name label in sequence, until the final step which would, rather than generating the address of the next DNS server, return the IP address of the host sought.
.The diagram illustrates this process for the host www.wikipedia.org.^ Default server: localhost Address: 127.0.0.1 > Let's try to resolve a host name, for example "www.NetBSD.org": .
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.The mechanism in this simple form would place a large operating burden on the root servers, with every search for an address starting by querying one of them.^ Operation of the root server system.
  • Government Domain Name Policy 19 January 2010 18:018 UTC www.choicefree.com [Source type: FILTERED WITH BAYES]

^ One of these servers would answer the query.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Most of the burden of finding an answer to the query is placed on the name server.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.Being as critical as they are to the overall function of the system, such heavy use would create an insurmountable bottleneck for trillions of queries placed every day.^ As such, they will tend to function as "natural monopolies" and should be regulated as a public trust and operated for the benefit of the Internet community as a whole.
  • Government Domain Name Policy 19 January 2010 18:018 UTC www.choicefree.com [Source type: FILTERED WITH BAYES]

^ Today, internet services are becoming cheaper, more specialized, and easier to use, with the result that every day more people and organizations create a persistent online presence.
  • Francis Hwang: Do Domain Names Matter? 19 January 2010 9:54 UTC fhwang.net [Source type: General]

^ In such situation ICAAN would seek for new domain operator… It probably would result in your domain being down for a long time… .
  • Get Creative With Your Domain Name - Smashing Magazine 19 January 2010 18:018 UTC www.smashingmagazine.com [Source type: FILTERED WITH BAYES]

.In practice caching is used in DNS servers to overcome this problem, and as a result, root nameservers actually are involved with very little of the total traffic.^ It then defines the root server information using the "."
  • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

^ Domain Names - On the Web, the domain name is that part of the Uniform Resource Locator (URL) that tells a domain name server using the domain name system (DNS) whether and where to forward a request for a Web page.
  • HHS Policy for Internet Domain Names 19 January 2010 9:54 UTC www.hhs.gov [Source type: FILTERED WITH BAYES]

^ From September 2000, ICANN will gradually be assuming total responsibility for the allocation of IP addresses, the management of the DNS and root server systems and the co-ordination of the assignment of protocol parameters.
  • Domain Names - Johnsons of Edinburgh - Patent & Trade Mark Attorneys 19 January 2010 9:54 UTC www.johnsonsofedinburgh.com [Source type: FILTERED WITH BAYES]

Circular dependencies and glue records

.Name servers in delegations appear listed by name, rather than by IP address.^ Name server list.
  • Registering, Managing, & Cancelling Domain Names 19 January 2010 18:018 UTC dnc.org.nz [Source type: FILTERED WITH BAYES]

^ Enter the zone name and IP address of the primary server when prompted.
  • How IT Works: Domain Name System 19 January 2010 9:54 UTC technet.microsoft.com [Source type: FILTERED WITH BAYES]

^ A (address) -- Specifies the IP address for a given name.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.This means that a resolving name server must issue another DNS request to find out the IP address of the server to which it has been referred.^ The server is commonly referred to as a name server.

^ The .sun.com server then returns the IP address of www.sun.com to the requesting DNS server.
  • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

^ The DNS server will load share resolver requests to this Host equally among the IP Addresses entered.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

.Since this can introduce a circular dependency if the nameserver referred to is under the domain for which it is authoritative, it is occasionally necessary for the nameserver providing the delegation to also provide the IP address of the next nameserver.^ Providing multiple IP addresses .
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ A domain name is an alias for an IP address.
  • Articles & News: Domain Name Information - Domain-Names 19 January 2010 9:54 UTC articles.pointshop.com [Source type: General]

^ IP addresses which fall under the 3.2.1.* IP space.
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

This record is called a glue record.
.For example, assume that the sub-domain en.wikipedia.org contains further sub-domains (such as something.en.wikipedia.org) and that the authoritative name server for these lives at ns1.something.en.wikipedia.org.^ Usually, these are servers which are authoritative for the domain of which they are a member.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The authoritative name servers must be updated when a change to the domain is made.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ Name servers can be authoritative for multiple zones, too.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.A computer trying to resolve something.en.wikipedia.org will thus first have to resolve ns1.something.en.wikipedia.org.^ Appreciation ICANNWatch.org ICANN evicted en masse hilarious userland essay something else Francis Hwang Rhizome Do Domain Names Matter?
  • Francis Hwang: Do Domain Names Matter? 19 January 2010 9:54 UTC fhwang.net [Source type: General]

^ Default server: localhost Address: 127.0.0.1 > Let's try to resolve a host name, for example "www.NetBSD.org": .
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.Since ns1 is also under the something.en.wikipedia.org subdomain, resolving ns1.something.en.wikipedia.org requires resolving something.en.wikipedia.org which is exactly the circular dependency mentioned above.^ Appreciation ICANNWatch.org ICANN evicted en masse hilarious userland essay something else Francis Hwang Rhizome Do Domain Names Matter?
  • Francis Hwang: Do Domain Names Matter? 19 January 2010 9:54 UTC fhwang.net [Source type: General]

^ As seen above, ns1.example.org would resolve to 3.2.1.2 .
  • Domain Name System (DNS) 19 January 2010 9:54 UTC docs.freebsd.org [Source type: Reference]

.The dependency is broken by the glue record in the nameserver of en.wikipedia.org that provides the IP address of ns1.something.en.wikipedia.org directly to the requestor, enabling it to bootstrap the process by figuring out where ns1.something.en.wikipedia.org is located.^ Providing multiple IP addresses .
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ Entries with A to the left of the IP address are A records.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ The pointer record contains the four octets of the IP address in reverse order followed by in-addr.arpa.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

Record caching

.Because of the large volume of requests generated in the DNS for the public Internet, the designers wished to provide a mechanism to reduce the load on individual DNS servers.^ Domain Names - On the Web, the domain name is that part of the Uniform Resource Locator (URL) that tells a domain name server using the domain name system (DNS) whether and where to forward a request for a Web page.
  • HHS Policy for Internet Domain Names 19 January 2010 9:54 UTC www.hhs.gov [Source type: FILTERED WITH BAYES]

^ Because the technology adds a lot of data to information stored in DNS databases, organizations managing the servers may have to upgrade, as well as add a new layer of administration for managing the security mechanism.
  • Standard For Securing Domain Name System Nears Finalization -- Security -- InformationWeek 19 January 2010 9:54 UTC www.informationweek.com [Source type: News]

^ We cannot control the rate at which the millions of name servers on the Internet are updated, but generally your domain should be available to Internet users within a very short period.
  • WDBC - Register .BIZ (DOT BIZ) Domain Names 19 January 2010 9:54 UTC www.wdbc.com [Source type: General]

.To this end, the DNS resolution process allows for caching of records for a period of time after an answer.^ The time-to-live tells the other DNS Servers how long they may cache the data before checking back with this Server to see if the data has changed.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Line 1: This is the Time To Live for lookups, which defines how long other DNS servers will cache that value before discarding it.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Renewal The process of reinitiating a domain name's registration for a specified period of time.
  • .: Goradia Infotech :. Web Services - Domain Registration - Domain Name Glossary 19 January 2010 18:018 UTC www.goradiainfotech.com [Source type: Reference]

.This entails the local recording and subsequent consultation of the copy instead of initiating a new request upstream.^ A master zone has the master copy of the zone's records and provides authoritative answers to lookup requests.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ The queried name server consults its local data (including its cache, which we're about to talk about), looking for the data requested.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.The time for which a resolver caches a DNS response is determined by a value called the time to live (TTL) associated with every record.^ DNS has a thing called the Time To Live.
  • Postal System and Domain Names 19 January 2010 9:54 UTC blog.domaintools.com [Source type: General]

^ Caching on DNS servers occurs within a controllable limit called the Time To Live (TTL).
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ If you know in advance that you will be changing IPs, shorten the current TTL (Time to Live), from the default value of 86400 (24 hours) to something like 3600 (1 hour) a full day or two beforehand.
  • Domain Name Systems - FAQS - Frequently asked questions 19 January 2010 9:54 UTC www.domainnamesystems.com [Source type: General]

.The TTL is set by the administrator of the DNS server handing out the authoritative response.^ Setting up a DNS server .
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ When set to 1, identifies the response as one made by an authoritative name server.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Compromise of DNS server’s authoritative data .

.The period of validity may vary from just seconds to days or even weeks.^ The new times are used to determine when the signature’s validity time period for the authenticated RRSet expires, rather than just when the RRSet should be expired.

^ Or, if a domain is transferred more than once during a 30 day period (just as an example), all prior transferees and transferrors would have to be notified.
  • BREAKING: First Ever Criminal Prosecution for Domain Name Theft Underway | Domain Name News 19 January 2010 9:54 UTC www.domainnamenews.com [Source type: General]

^ There is a chance the domain may have been sold to another party after the 10 day period, you then have no opportunity to renew the domain.
  • Domain Name Systems - FAQS - Frequently asked questions 19 January 2010 9:54 UTC www.domainnamesystems.com [Source type: General]

.As a noteworthy consequence of this distributed and caching architecture, changes to DNS records do not propagate throughout the network immediately, but require all caches to expire and refresh after the TTL. RFC 1912 conveys basic rules for determining appropriate TTL values.^ The DNS has a distributed, client-server architecture.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ However, propagation of DNS database changes amongst the root servers is quite efficient.
  • "PC-Unix Connection" The Domain Name System - Network Computing 19 January 2010 9:54 UTC www.networkcomputing.com [Source type: General]

^ Web browsers, email clients, and other network applications rely on zone records to contact the appropriate server.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

.Some resolvers may override TTL values, as the protocol supports caching for up to 68 years or no caching at all.^ This is because the DNS RR explicitly contains the HIT type and algorithm, while some protocols may prefer to use a prefix to indicate the HIT type.
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ A large TTL will shorten the average time it takes to resolve information in your domain because the data can be cached longer.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ A caching only name server has no local zones; all the queries it receives are forwarded to the root servers and the replies are accumulated in the local cache.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

Negative caching, i.e. the caching of the fact of non-existence of a record, is determined by name servers authoritative for a zone which must include the Start of Authority (SOA) record when reporting no data of the requested type exists. .The value of the MINIMUM field of the SOA record and the TTL of the SOA itself is used to establish the TTL for the negative answer.^ The Authority section is filled with either SOA or NS records belonging to the zone of authority for the owner name of the RR(s) in the Answer section.

^ The Min TTL or Minimum Time-To-Live value is used by any other Domain Name Server that queries any piece of data within this Zone.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Section 4 SOA record The SOA record (Start of Authority) that defines the configuration of the name server of the domain name shall comply with the following: 1) The MNAME field shall contain the name of the primary name server of the domain name.
  • Safenames : Regulations - FI, FI, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: FILTERED WITH BAYES]

Reverse lookup

.The term reverse lookup refers to performing a DNS query to find one or more DNS names associated with a given IP address.^ Through this procedure, the DNS translates names to IP addresses.
  • Domain Name System 19 January 2010 9:54 UTC www.javabeat.net [Source type: FILTERED WITH BAYES]

^ By doing this, using IP addresses to find DNS host names are handled just like DNS host name lookups to find IP addresses.

^ If it does not find that particular domain name, it refers the query to one of the root servers.
  • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

.The DNS stores IP addresses in form of specially formatted names as pointer (PTR) records using special domains.^ This is a special "domain" which is used to do reverse-lookup of IP addresses back into hostnames.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Pointer (PTR) : Stores the domain name of a given IP address (reverse lookup).
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ Each domain name corresponds to a numeric IP (Internet Protocol) address.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

.For IPv4, the domain is in-addr.arpa. For IPv6, the reverse lookup domain is ip6.arpa.^ The pseudodomains inaddr-arpa for IPv4 and IP6.arpa for IPv6 were created for the purpose of reverse translation.
  • Domain Name System 19 January 2010 9:54 UTC www.javabeat.net [Source type: FILTERED WITH BAYES]

^ The pointer record contains the four octets of the IP address in reverse order followed by in-addr.arpa.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ This is a special "domain" which is used to do reverse-lookup of IP addresses back into hostnames.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

The IP address is represented as a name in reverse-ordered octet representation for IPv4, and reverse-ordered nibble representation for IPv6.
.When performing a reverse lookup, the DNS client converts the address into these formats, and then queries the name for a PTR record following the delegation chain as for any DNS query.^ Pointer (PTR) : Stores the domain name of a given IP address (reverse lookup).
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ These records are used for reverse name lookups.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ DNS clients are configured with the addresses of DNS servers.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.For example, the IPv4 address 208.80.152.2 is represented as a DNS name as 2.152.80.208.in-addr.arpa.^ The pointer record contains the four octets of the IP address in reverse order followed by in-addr.arpa.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ Looking at a typical DNS address, www.mcslp.com, the name can be divided by splitting up the contents by a period, starting with the fragment on the far right ( com ).
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ Postal Mail being addressed with DNS entries but I don’t believe that the DNS entry should have to exist under a special name space.
  • Postal System and Domain Names 19 January 2010 9:54 UTC blog.domaintools.com [Source type: General]

.The DNS resolver begins by querying the root servers, which point to ARIN's servers for the 208.in-addr.arpa zone.^ A DNS server can be authoritative for several zones.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Querying a DNS server .
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ The requested domain name does not fall within the zone of company1s DNS server, and consequently, the server does not hold the required information.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

.From there the Wikimedia servers are assigned for 152.80.208.in-addr.arpa, and the PTR lookup completes by querying the wikimedia nameserver for 2.152.80.208.in-addr.arpa, which results in an authoritative response.^ When nameservers receive responses to queries, they can cache the results.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ If the server passes the query onto another DNS server that has incorrect information, whether placed there intentionally or unintentionally, then cache poising can occur [CA97].

^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

Client lookup

DNS resolution sequence.
.Users generally do not communicate directly with a DNS resolver.^ In general, the user does not generate queries directly, but instead makes a request to a resolver which in turn sends one or more queries to name servers and deals with the error conditions and referrals that may result.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ A resolver will typically be a system routine that is directly accessible to user programs; hence no protocol is necessary between the resolver and the user program.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ By sending back the negative response for a DNS name that could otherwise be resolved, results in a DoS for the client wishing to communicate in some manner with the DNS name in the query.

.Instead DNS resolution takes place transparently in applications programs such as web browsers, e-mail clients, and other Internet applications.^ Web browsers, email clients, and other network applications rely on zone records to contact the appropriate server.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ Security aware servers, resolvers, and applications can then take advantage of this technology to assure that the information obtained from a security aware DNS server is authentic and has not been altered.

^ This document reports the conclusions of an assessment of the current state and the future prospects of the DNS and its interactions with Internet navigation, including its uses as a means of navigation itself and as an infrastructure for navigation by other means.
  • Signposts in Cyberspace: The Domain Name System and Internet Navigation 19 January 2010 9:54 UTC www.nap.edu [Source type: FILTERED WITH BAYES]

.When an application makes a request that requires a domain name lookup, such programs send a resolution request to the DNS resolver in the local operating system, which in turn handles the communications required.^ Make the Most of your Domain Name !
  • Register Domain Name - Domain Registration 19 January 2010 9:54 UTC www.searchfit.info [Source type: General]

^ How domain name resolution works .
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ Introduction Resolvers are programs that interface user programs to domain name servers.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.The DNS resolver will almost invariably have a cache (see above) containing recent lookups.^ The time-to-live tells the other DNS Servers how long they may cache the data before checking back with this Server to see if the data has changed.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ In a nutshell this file is telling the resolver that this machine belongs to the "diverge.org" domain, which means that lookups that contain only a hostname without a "."
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The name.root file contains the names of root domain servers used to initialize the WebTen DNS cache.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

.If the cache can provide the answer to the request, the resolver will return the value in the cache to the program that made the request.^ The resolver handles: Querying a name server Interpreting responses (which may be resource records or an error) Returning the information to the programs that requested it In BIND , the resolver is just a set of library routines that is linked into programs such as telnet and ftp .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ A master zone has the master copy of the zone's records and provides authoritative answers to lookup requests.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ After retrieving the PTR record, another query is sent out requesting the "A" record using the FQDN specified in the answer section of the PTR record returned.

.If the cache does not contain the answer, the resolver will send the request to one or more designated DNS servers.^ What does a DNS server do?
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

^ If it does, it will send the query to one of them.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ The local nameserver must then send its request to one of these servers.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.In the case of most home users, the Internet service provider to which the machine connects will usually supply this DNS server: such a user will either have configured that server's address manually or allowed DHCP to set it; however, where systems administrators have configured systems to use their own DNS servers, their DNS resolvers point to separately maintained nameservers of the organization.^ Setting up a DNS server .
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ Check with a network administrator to ensure that DNS servers are configured properly.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ However, some providers might allow companies to use their own domain (e.g.
  • The Domain Name System (DNS) 19 January 2010 18:018 UTC www.dialogic.com [Source type: FILTERED WITH BAYES]

.In any event, the name server thus queried will follow the process outlined above, until it either successfully finds a result or does not.^ If it does not find that particular domain name, it refers the query to one of the root servers.
  • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

^ The name server must concurrently process queries that arrive from resolvers.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ In a recursive query, the server does the asking and returns the final result.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.It then returns its results to the DNS resolver; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request.^ They use tiny Time-To-Live values to prevent result caching, thereby forcing all requests to come to authoritative servers, which can give different replies to different clients.
  • ISC-TN-2004-2: The role of the Domain Name System in the development of new Internet services 19 January 2010 18:018 UTC ftp.isc.org [Source type: FILTERED WITH BAYES]

^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The DNS server will load share resolver requests to this Host equally among the IP Addresses entered.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

Broken resolvers

.An additional level of complexity emerges when resolvers violate the rules of the DNS protocol.^ Lower-Level Transport Either TCP or UDP can be used to transport DNS protocol messages, connecting to server port 53 for either.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Resolving these server names, in turn, depends on additional name resolutions, creating complex interdependencies among DNS servers.
  • Perils of Transitive Trust in the Domain Name System 19 January 2010 9:54 UTC www.usenix.org [Source type: FILTERED WITH BAYES]

^ In addition to the DNS, there are the web browsers and e-mail, they're all tools for using the Internet and many more will emerge from research, over time.
  • The Domain Name System: Where do we go from Here? 19 January 2010 9:54 UTC commdocs.house.gov [Source type: Original source]

.A number of large ISPs have configured their DNS servers to violate rules (presumably to allow them to run on less-expensive hardware than a fully-compliant resolver), such as by disobeying TTLs, or by indicating that a domain name does not exist just because one of its name servers does not respond.^ If it does not find that particular domain name, it refers the query to one of the root servers.
  • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

^ Edit your /etc/resolv.conf file to configure the domain and DNS servers .
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ This happens when the referenced name does not exist.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

[10]
.As a final level of complexity, some applications (such as web-browsers) also have their own DNS cache, in order to reduce the use of the DNS resolver library itself.^ Web browsers, email clients, and other network applications rely on zone records to contact the appropriate server.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ If the remote system does not have access to DNS, use the explicit IP address of the system on which Web Ten is running.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

.This practice can add extra difficulty when debugging DNS issues, as it obscures the freshness of data, and/or what data comes from which cache.^ The time-to-live tells the other DNS Servers how long they may cache the data before checking back with this Server to see if the data has changed.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Within the package comes a set of small programs that perform several kinds of statistics on the cached data.
  • Taking Care of Your Domain 19 January 2010 9:54 UTC www.ripe.net [Source type: FILTERED WITH BAYES]

^ The inference is that the data did not come from a zone, but from a cache.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.These caches typically use very short caching times — on the order of one minute.^ An attacker can give the injected cache a short time to live making it appear and disappear quickly enough to avoid detection.

^ An attacker makes use of cache poisoning for one of two reasons.

^ In order to maintain consistency between these servers, one is usually configured as the primary server, and all administrative changes are made on this server.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.Internet Explorer offers a notable exception: recent versions cache DNS records for half an hour.^ Kashpureff injected bogus information into DNS caches around the world concerning DNS information pertaining to Network Solutions Inc.’s (NSI) Internet’s Network Information Center (InterNIC).

^ DNS Management Today:   In recent years, commercial use of the Internet has expanded rapidly.
  • Government Domain Name Policy 19 January 2010 18:018 UTC www.choicefree.com [Source type: FILTERED WITH BAYES]

^ Web Ten includes a complete implementation of the Berkeley Internet Named Domain (BIND) DNS, version 8.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

[11]

Other applications

The system outlined above provides a somewhat simplified scenario. The Domain Name System includes several other functions:
.
  • Hostnames and IP addresses do not necessarily match on a one-to-one basis.^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
    • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

    ^ This is a special "domain" which is used to do reverse-lookup of IP addresses back into hostnames.
    • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

    ^ From there the query may be referred to a number of other domain name servers, until it finds one that knows the IP address, at which point the IP address is returned to the workstation.
    • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

    .Many hostnames may correspond to a single IP address: combined with virtual hosting, this allows a single machine to serve many web sites.^ IP-based virtual hosts use the actual IP address of each virtual host.
    • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

    ^ They are also known as IP address-based virtual hosts.
    • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

    ^ Remember that you can use pretty much any combination of domain name registrar and web hosting company.
    • Domain Name Guide - Site5Wiki 19 January 2010 9:54 UTC wiki.site5.com [Source type: General]

    .Alternatively a single hostname may correspond to many IP addresses: this can facilitate fault tolerance and load distribution, and also allows a site to move physical location seamlessly.
  • There are many uses of DNS besides translating names to IP addresses.^ They can use their IP Physical address instead.
    • Postal System and Domain Names 19 January 2010 9:54 UTC blog.domaintools.com [Source type: General]

    ^ It does this by overseeing the distribution of unique IP addresses and domain names.
    • ICANN | FAQs 19 January 2010 9:54 UTC www.icann.org [Source type: FILTERED WITH BAYES]

    ^ The DNS server determines the IP address that corresponds to the domain name requested in the lookup.
    • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

    .For instance, Mail transfer agents use DNS to find out where to deliver e-mail for a particular address.^ Companies running their own mail services would also want to ensure DNS service to correctly map IP addresses to their mail domains.
    • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

    ^ An intruder can make use of DNS tools to automatically query, one by one, every IP address in a domain space in an attempt to learn the DNS host name or to find IP addresses that are not assigned.

    ^ All valid DNS servers on the Internet can eventually find DNS information on any address by following the appropriate lookup through this top-level approach.
    • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

    .The domain to mail exchanger mapping provided by MX records accommodates another layer of fault tolerance and load distribution on top of the name to IP address mapping.
  • E-mail Blacklists: The DNS system is used for efficient storage and distribution of IP addresses of blacklisted e-mail hosts.^ By doing this, using IP addresses to find DNS host names are handled just like DNS host name lookups to find IP addresses.

    ^ The Domain Name System (DNS), which resolves host names to IP addresses, is critical to the integrity of Internet services and applications.
    • Perils of Transitive Trust in the Domain Name System 19 January 2010 9:54 UTC www.usenix.org [Source type: FILTERED WITH BAYES]

    ^ The directory essentially assigns host names to IP addresses.

    .The usual method is putting the IP address of the subject host into the sub-domain of a higher level domain name, and resolve that name to different records to indicate a positive or a negative.^ Domains names can be configured to point to any web hosting provider by 3 different methods.
    • Frequently Asked Questions about Domain Names 19 January 2010 9:54 UTC mapname.com [Source type: General]

    ^ The directory essentially assigns host names to IP addresses.

    ^ The difference is that IP addresses get more specific from left to right, while domain names get less specific from left to right.
    • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

    .A hypothetical example using blacklist.com,
    • 102.3.4.5 is blacklisted => Creates 5.4.3.102.blacklist.com and resolves to 127.0.0.1
    • 102.3.4.6 is not => 6.4.3.102.blacklist.com is not found, or default to 127.0.0.2
    • E-mail servers can then query blacklist.com through the DNS mechanism to find out if a specific host connecting to them is in the blacklist.^ Alice creates a web page, using http://faß.de "> (or http://TÜRKIYE.com ).
      • FAQ - International Domain Name (IDN) 19 January 2010 9:54 UTC www.unicode.org [Source type: FILTERED WITH BAYES]

      ^ An intruder can make use of DNS tools to automatically query, one by one, every IP address in a domain space in an attempt to learn the DNS host name or to find IP addresses that are not assigned.

      ^ All valid DNS servers on the Internet can eventually find DNS information on any address by following the appropriate lookup through this top-level approach.
      • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

      .Today many of such blacklists, either free or subscription-based, are available mainly for use by email administrators and anti-spam software.
  • Software Updates: many anti-virus and commercial software now use the DNS system to store version numbers of the latest software updates so client computers do not need to connect to the update servers every time.^ These computers are in essence DNS clients.

    ^ IP-based virtual hosting can use host names if DNS is available.
    • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

    ^ In the mean time, the latest version is available from ns.
    • Taking Care of Your Domain 19 January 2010 9:54 UTC www.ripe.net [Source type: FILTERED WITH BAYES]

    For these types of applications, the cache time of the DNS records are usually shorter.
  • Sender Policy Framework and DomainKeys, instead of creating their own record types, were designed to take advantage of another DNS record type, the TXT record.
  • To provide resilience in the event of computer failure, multiple DNS servers are usually provided for coverage of each domain, and at the top level, thirteen very powerful root servers exist, with additional "copies" of several of them distributed worldwide via Anycast.
  • Dynamic DNS (also referred to as DDNS) provides clients the ability to update their IP address in the DNS after it changes due to mobility, e.g.

Protocol details

.DNS primarily uses User Datagram Protocol (UDP) on port number 53[12] to serve requests.^ And the DNS was used for about 12 years (1982-94) without creating any significant public policy issues.
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ Abstract This document specifies two new resource records for the Domain Name System (DNS), and how to use them with the Host Identity Protocol (HIP).
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ InterNIC uses the term to refer to name servers , the computers that have both the software and the data required to resolve domain names to Internet Protocol (IP) numbers.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

.DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server.^ If the server passes the query onto another DNS server that has incorrect information, whether placed there intentionally or unintentionally, then cache poising can occur [CA97].

^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Security aware DNS servers are the source of all security-related information within the DNS. Any given primary DNS server has three main functions: manage authoritative zone information, manage the caching of DNS information, and respond to client queries.

.The Transmission Control Protocol (TCP) is used when the response data size exceeds 512 bytes, or for tasks such as zone transfers.^ Slave zones use zone transfers to get copies of the master zone data.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ ICANN's role is very limited, and it is not responsible for many issues associated with the Internet, such as financial transactions, Internet content control, spam (unsolicited commercial email), Internet gambling, or data protection and privacy.
  • ICANN | FAQs 19 January 2010 9:54 UTC www.icann.org [Source type: FILTERED WITH BAYES]

^ The two most common transactions are DNS zone transfers and DNS queries/responses.

.Some operating systems, such as HP-UX, are known to have resolver implementations that use TCP for all queries, even when UDP would suffice.^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The worst of all possible cases is an implementation of IDNA2008 that uses local mappings.
  • FAQ - International Domain Name (IDN) 19 January 2010 9:54 UTC www.unicode.org [Source type: FILTERED WITH BAYES]

^ All of the TLD operators have agreed to implement the UDRP, yet each has proposed its own nuances for dispute resolution.
  • Domain Names - Internet Law Program 19 January 2010 18:018 UTC cyber.law.harvard.edu [Source type: FILTERED WITH BAYES]

DNS resource records

.A Resource Record (RR) is the basic data element in the domain name system.^ Resource Records The data associated with domain names are contained in resource records , or RR s .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ The domain system provides: - Standard formats for resource data.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.Each record has a type (A, MX, etc.^ To indicate the RR type of the RRSet (i.e., NS, PTR, MX, etc.

), an .expiration time limit, a class, and some type-specific data.^ The most common reasons for creating a new class are the necessity for a new data format for existing types or a desire for a separately managed version of the existing name space.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ The DNS tags all data with a class as well as the type, so that we can allow parallel use of different formats for data of type address.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ If the name, class, type, and data are the same for two or more records then duplicate records exist for the same DNS name.

.Resource records of the same type define a resource record set.^ Authority count 16-bit field that defines the number of name server resource records in the authority section.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Consequently, we need a means to translate a domain name into an HI. Using the DNS for this translation is pretty straightforward: We define a new HIPHI (HIP HI) resource record.
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ The following Resource Records are commonly used (a number of others are defined but not often used, or no longer used).
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.The order of resource records in a set, returned by a resolver to an application, is undefined, but often servers implement round-robin ordering to achieve load balancing.^ If there is a tie with some RRs, the server should return a set of RRs ordered in a load balancing manner (e.g., round robin).
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ The resolver handles: Querying a name server Interpreting responses (which may be resource records or an error) Returning the information to the programs that requested it In BIND , the resolver is just a set of library routines that is linked into programs such as telnet and ftp .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Authority count 16-bit field that defines the number of name server resource records in the authority section.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

.DNSSEC, however, works on complete resource record sets in a canonical order.^ When a name server fails to find a desired RR in the resource set associated with the domain name, it checks to see if the resource set consists of a CNAME record with a matching class.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ The set of resource information associated with a particular name is composed of separate resource records (RRs).
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ RRs are grouped into resources records sets (RRSets).

.When sent over an IP network, all records use the common format specified in RFC 1035 and shown below.^ Abstract This document specifies two new resource records for the Domain Name System (DNS), and how to use them with the Host Identity Protocol (HIP).
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ It is common for these records to be used to point to hosts providing a particular service, such as an FTP or HTTP server.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ After retrieving the PTR record, another query is sent out requesting the "A" record using the FQDN specified in the answer section of the PTR record returned.

RR (Resource record) fields
Field Description Length (octets)
NAME Name of the node to which this record pertains. (variable)
TYPE Type of RR. For example, MX is type 15. 2
CLASS Class code. 2
TTL Unsigned time in seconds that RR stays valid, maximum is 2147483647. 4
RDLENGTH Length of RDATA field. 2
RDATA Additional RR-specific data. (variable)
.NAME is the fully qualified domain name of the node in the tree.^ The domain name of a node is the list of the labels on the path from the node to the root of the tree.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ It is not necessary to append the Domain Name at the end of the Host Name (i.e., it is not necessary to enter fully qualified Host Names).
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ NS: Name Server This record type is used to delegate a sub-tree of the Domain Name space to another nameserver.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.On the wire, the name may be shortened using label compression where ends of domain names mentioned earlier in the packet can be substituted for the end of the current domain name.^ The domain name may also be listed for auction.
  • REF Sales Systems - Domain Registration Agreement 19 January 2010 18:018 UTC www.refsalessystems.com [Source type: Reference]

^ The domain names MUST NOT be compressed.
  • draft-ietf-hip-dns-00 - Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 19 January 2010 9:54 UTC tools.ietf.org [Source type: Reference]

^ Current use of domain extensions .
  • Get Creative With Your Domain Name - Smashing Magazine 19 January 2010 18:018 UTC www.smashingmagazine.com [Source type: FILTERED WITH BAYES]

TYPE is the record type. .It indicates the format of the data and it gives a hint of its intended use.^ The DNS tags all data with a class as well as the type, so that we can allow parallel use of different formats for data of type address.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ This function will often use the DNS format for all RR data instead of the local host's, and returns all RR content (e.g., TTL) instead of a processed form with local quoting conventions.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ When the resolver performs the indicated function, it usually has one of the following results to pass back to the client: - One or more RRs giving the requested data.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.For example, the A record is used to translate from a domain name to an IPv4 address, the NS record lists which name servers can answer lookups on a DNS zone, and the MX record specifies the mail server used to handle mail for a domain specified in an e-mail address (see also List of DNS record types).^ By doing this, using IP addresses to find DNS host names are handled just like DNS host name lookups to find IP addresses.

^ NS: Name Server This record type is used to delegate a sub-tree of the Domain Name space to another nameserver.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Name servers can be authoritative for multiple zones, too.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.RDATA is data of type-specific relevance, such as the IP address for address records, or the priority and hostname for MX records.^ Entries with A to the left of the IP address are A records.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

^ MX: Mail eXchange This record contains the FQDN for a host that will accept SMTP electronic mail for the named domain, together with a priority value used to select an MX host when relaying mail.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The pointer record contains the four octets of the IP address in reverse order followed by in-addr.arpa.
  • Peachpit: Using Network Services in Mac OS X > Domain Name System 19 January 2010 9:54 UTC www.peachpit.com [Source type: General]

.Well known record types may use label compression in the RDATA field, but "unknown" record types must not (RFC 3597).^ He added that where an organisation wishes to use a domain name globally it must take into account that in some countries there may be infringement of existing rights.
  • Domain Names - Johnsons of Edinburgh - Patent & Trade Mark Attorneys 19 January 2010 9:54 UTC www.johnsonsofedinburgh.com [Source type: FILTERED WITH BAYES]

^ NS: Name Server This record type is used to delegate a sub-tree of the Domain Name space to another nameserver.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ TCP must be used for zone transfers, however, because of the danger of dropping records with an unreliable delivery protocol such as UDP. .
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

.The CLASS of a record is set to IN (for Internet) for common DNS records involving Internet hostnames, servers, or IP addresses.^ DNS clients are configured with the addresses of DNS servers.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ This field contains the IP address of the DNS server.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Enter an IP Addresses in the Internet dot ("."
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

In addition, the classes CH (Chaos) and HS (Hesiod) exist. .Each class is a completely independent tree with potentially different delegations of DNS zones.^ Zone A part of the DNS tree, that is treated as a unit.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Other threats to the DNS include zone transfers that can leak information concerning internal networks to a potential attacker.

^ The DNS tags all data with a class as well as the type, so that we can allow parallel use of different formats for data of type address.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.In addition to resource records defined in a zone file, the domain name system also defines several request types that are used only in communication with other DNS nodes (on the wire), such as when performing zone transfers (AXFR/IXFR) or for EDNS (OPT).^ This page is used to enter the Domain Name of a Primary Zone to be managed by this system.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Resource Records The data associated with domain names are contained in resource records , or RR s .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ This page is used to enter the Domain Name of a Secondary Zone to be managed by this system.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

Wildcard DNS records

.The domain name system supports wildcard domain names which are names that start with the asterisk label, '*', e.g., *.example.^ Typically in an FQDN, the left most label is the host name, while the next label to the right is the local domain to which the host belongs.

^ RFC 3007 ] Secure Domain Name System (DNS) Dynamic Update.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ When a user needs to type a domain name, the length of each label is omitted and the labels are separated by dots ("."
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

[2][13] .DNS records belonging to wildcard domain names specify rules for generating resource records within a single DNS zone by substituting whole labels with matching components of the query name, including any specified descendants.^ Resource Records The data associated with domain names are contained in resource records , or RR s .
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ The Domain Name must match the Domain Name for an existing Zone.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ When the query name or a name between the wildcard domain and the query name is know to exist.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.For example, in the DNS zone x.example, the following configuration specifies that all subdomains (including subdomains of subdomains) of x.example use the mail exchanger a.x.example.^ Most RRs are single line entries; the sole exception here is the SOA RR, which uses "(" to start a multi-line RR and ")" to show the end of a multi-line RR. Since the class of all RRs in a zone must be the same, only the first RR in a zone need specify the class.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ The new Primary Zone Name will now be included (in alphabetical order) in the table of Primary Zones in the DNS Settings Page.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ You need this setting if you want your server to resolve addresses outside of your network (for example, on the Internet), in addition to those inside your network for the configured zones.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.The records for a.x.example are needed to specify the mail exchanger.^ This Host Name is often used to specify the default Mail Exchanger for an entire Domain or to specify a default IP Address for attempts to access this Domain without explicitly specifying a Host Name.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ The mail exchanger records are used by mail transport agents like sendmail and postfix when looking up where to send e-mail.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ For example, if the question is for an MX record for FreeSoft.org, the answer will currently point to mail.adnc.com.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

.As this has the result of excluding this domain name and its subdomains from the wildcard matches, all subdomains of a.x.example must be defined in a separate wildcard statement.^ The Domain Name must match the Domain Name for an existing Zone.
  • 11.0 Domain Name System (DNS) 19 January 2010 9:54 UTC www.tenon.com [Source type: Reference]

^ Example of inverse domains and the Domain Name Space .

^ A subdomain's domain name ends with the domain name of its parent domain.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

X.EXAMPLE.       MX   10 A.X.EXAMPLE.
*.X.EXAMPLE.     MX   10 A.X.EXAMPLE.
*.A.X.EXAMPLE.   MX   10 A.X.EXAMPLE.
A.X.EXAMPLE.     MX   10 A.X.EXAMPLE.
A.X.EXAMPLE.     AAAA 2001:db8::1
.The role of wildcard records was refined in RFC 4592, because the original definition in RFC 1034 was incomplete and resulted in misinterpretations by implementers.^ RFC 883 ] DOMAIN NAMES - IMPLEMENTATION and SPECIFICATION. Obsoleted by: RFC 1034 , RFC 1035 .
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

[13]

Protocol extensions

.The original DNS protocol had limited provisions for extension with new features.^ DNS. Keeping SiteFinder out of the center leaves the greatest flexibility in the netowrk for those who want to add new protocols, services, and features on the ends.
  • Domain Name Rights Coalition: Domain Names Archives 19 January 2010 18:018 UTC www.netpolicy.com [Source type: General]

^ The scope of the security extensions to the DNS can be summarized into three services: key distribution, data origin authentication, and transaction and request authentication.

^ This paper gives an overview of the DNS, its security weaknesses, and the new security extensions being worked on by the IETF’s DNSSEC Working Group (WG).

.In 1999, Paul Vixie published in RFC 2671 an extension mechanism, called Extension mechanisms for DNS (EDNS) that introduced optional protocol elements without increasing overhead when not in use.^ RFC 2671 ] Extension Mechanisms for DNS (EDNS0).
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ And the DNS was used for about 12 years (1982-94) without creating any significant public policy issues.
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ RFC 1612 ] DNS Resolver MIB Extensions.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

.This was accomplished through the OPT pseudo-resource record that only exists in wire transmissions of the protocol, but not in any zone files.^ The data files contain resource records that describe the zone.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ A computer that has both the software and the data ( zone file ) needed to resolve domain names to Internet Protocol (IP) numbers.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

^ In addition, special Types exist to wildcard mail records and to trigger zone transfers.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

.Initial extensions were also suggested (EDNS0), such as increasing the DNS message size in UDP datagrams.^ RFC 2671 ] Extension Mechanisms for DNS (EDNS0).
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Lower-Level Transport Either TCP or UDP can be used to transport DNS protocol messages, connecting to server port 53 for either.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

Dynamic zone updates

.Dynamic DNS updates use the UPDATE DNS opcode to add or remove resource records dynamically from a zone data base maintained on an authoritative DNS server.^ DNS servers that store Resource Records for a zone, whether they be primary or secondary servers, are said to be authoritative for the zone.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Name servers can be authoritative for multiple zones, too.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ The data files contain resource records that describe the zone.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

The feature is described in RFC 2136. .This facility is useful to register network clients into the DNS when they boot or become otherwise available on the network.^ Registration Forms from Network Solutions Access to forms used to register a new contact NIC handle and to modify existing contact NIC handle information.

^ Clients of the domain system should be able to identify trusted name servers they prefer to use before accepting referrals to name servers outside of this "trusted" set.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Setting up your own domain server can be useful both if you are hosting a public DNS domain available on the Internet, and if you want to configure your own DNS information to resolve the addresses and other information within your private network.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.Since a booting client may be assigned a different IP address each time from a DHCP server, it is not possible to provide static DNS assignments for such clients.^ The DNS has a distributed, client-server architecture.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The mcslp.com DNS server returns the IP address to the DNS server.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ DNS clients are configured with the addresses of DNS servers.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

Security issues

.DNS was not originally designed with security in mind, and thus has a number of security issues.^ However, the original DNS protocol specifications did not include security.

^ In 1994, the IETF formed a working group to provide security extensions to the DNS protocol in response to the security issues surrounding the DNS. These extensions are commonly referred to as DNSSEC extensions.

^ Performance issues are a concern for the security extensions to the DNS protocol and several aspects in the design of DNSSEC are targeted to avoid the overhead associated with processing the extensions.

.One class of vulnerabilities is DNS cache poisoning, which tricks a DNS server into believing it has received authentic information when, in reality, it has not.^ The majority of the weaknesses within the DNS fall into one of the following categories: Cache poisoning, client flooding, dynamic update vulnerability, information leakage, and compromise of the DNS server’s authoritative database.

^ If the server passes the query onto another DNS server that has incorrect information, whether placed there intentionally or unintentionally, then cache poising can occur [CA97].

^ Finally, the "nameserver" line gives the IP addresses of one or more DNS servers that should be used to resolve DNS queries.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.DNS responses are traditionally not cryptographically signed, leading to many attack possibilities; The Domain Name System Security Extensions (DNSSEC) modifies DNS to add support for cryptographically signed responses.^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ In the Domain Name System (DNS), the highest level of the hierarchy after the root.
  • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

^ Because a domain name can be in many subtrees, a domain name can also be in many domains.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.There are various extensions to support securing zone transfer information as well.^ The zone, example.org , is a secured zone and lets assume for this example only, that there isn’t a size constraint on the response message.

^ Other threats to the DNS include zone transfers that can leak information concerning internal networks to a potential attacker.

^ For redundancy, it is common (and often administratively required) that there be more than one nameserver providing information on a zone.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

.Even with encryption, a DNS server could become compromised by a virus (or for that matter a disgruntled employee) that would cause IP addresses of that server to be redirected to a malicious address with a long TTL.^ The mcslp.com DNS server returns the IP address to the DNS server.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ DNS clients are configured with the addresses of DNS servers.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The DNS server returns the IP address to the client.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.This could have far-reaching impact to potentially millions of Internet users if busy DNS servers cache the bad IP data.^ Compromise of DNS server’s authoritative data .

^ An Internet server is a program that interacts with user programs.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

^ If the server passes the query onto another DNS server that has incorrect information, whether placed there intentionally or unintentionally, then cache poising can occur [CA97].

.This would require manual purging of all affected DNS caches as required by the long TTL (up to 68 years).^ The meaning of the TTL field is a time limit on how long an RR can be kept in a cache.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Line 1: This is the Time To Live for lookups, which defines how long other DNS servers will cache that value before discarding it.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ Figure 2.1: The structure of the DNS name space 2.1.1 Domain Names Each node in the tree has a text label (without dots) that can be up to 63 characters long.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.Some domain names can spoof other, similar-looking domain names.^ Others allow multiple domain names.
  • Domain Names - Johnsons of Edinburgh - Patent & Trade Mark Attorneys 19 January 2010 9:54 UTC www.johnsonsofedinburgh.com [Source type: FILTERED WITH BAYES]

^ Similar to trademark infringement, domain names also face some servere infringement.
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ For some top-level domains, the results of a successful search will contain only technical information about the registered domain name and referral information for the registrar of the domain name.
  • ICANN | FAQs 19 January 2010 9:54 UTC www.icann.org [Source type: FILTERED WITH BAYES]

.For example, "paypal.com" and "paypa1.com" are different names, yet users may be unable to tell the difference when the user's typeface (font) does not clearly differentiate the letter l and the numeral 1.^ For example, a user may have mistyped a host name.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ For example, hp.com is both the name of the Hewlett-Packard Company's domain and the domain name of a host that runs HP 's main web server.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ From our example, www.mcslp.com, the 'com' is example of a top-level domain (TLD) name that organizes the names by organizational or regional structure.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

.This problem is much more serious in systems that support internationalized domain names, since many characters that are different, from the point of view of ISO 10646, appear identical on typical computer screens.^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ From the resolver's point of view, the domain system is composed of an unknown number of name servers.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ Because a domain name can be in many subtrees, a domain name can also be in many domains.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

This vulnerability is often exploited in phishing.
.Techniques such as Forward Confirmed reverse DNS can also be used to help validate DNS results.^ DNS Lookups Normal resource records lookups are done with UDP. An "intelligent retransmission" is to be used, though one is not specified in the protocol, resulting in a mix of poor strategies with good ones.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Because they're so important, DNS provides mechanisms - such as caching, which we'll discuss a little later - to help offload the root name servers.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ This type of query makes up such a vast majority of DNS queries that we use the term "query" to mean standard query unless otherwise specified.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

Domain name registration

.The right to use a domain name is delegated by domain name registrars which are accredited by the Internet Corporation for Assigned Names and Numbers (ICANN), the organization charged with overseeing the name and number systems of the Internet.^ ICANN is also the successor to the Internet Assigned Numbers Authority (IANA), which historically co-ordinated the IP addressing and domain name system.
  • Domain Names - Johnsons of Edinburgh - Patent & Trade Mark Attorneys 19 January 2010 9:54 UTC www.johnsonsofedinburgh.com [Source type: FILTERED WITH BAYES]

^ The charge for registering, a domain name.
  • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

.In addition to ICANN, each top-level domain (TLD) is maintained and serviced technically by an administrative organization, operating a registry.^ One of the worldwide top level domains.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

^ A top-level domain name (or "TLD") is the suffix at the end of the domain.
  • Expired Domain Names 19 January 2010 9:54 UTC www.bizmint.com [Source type: General]

^ TLDs, other than ccTLDs, as determined by ICANN; Geographical-type .JP domain names that are defined as metropolitan, prefectural, and municipal labels; Names of primary and secondary educational organizations Names of organizations related to Internet management; Names required for .JP domain name operations; and Character strings which may be confused with ASCII-converted Japanese domain names.

.A registry is responsible for maintaining the database of names registered within the TLD it administers.^ This organisation is responsible for establishing and maintaining conventions further down the tree, within its own domain.
  • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

^ The Stanford Research Institute’s Network Information Center (SRI-NIC) became the responsible authority for maintaining unique host names for the Internet.

^ Every TLD registry - generic or country code - has its own prices, policies, and procedures that registrants (name holders) in that registry are subject to.
  • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

.The registry receives registration information from each domain name registrar authorized to assign names in the corresponding TLD and publishes the information using a special service, the whois protocol.^ You acknowledge that Registry Policies are applicable to all registrars and domain name registrants.

^ National Domain Name Registry, et.
  • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

^ This information is required for domain name registration.
  • Glossary of Domain Name Registration Terms By AboutDomains 19 January 2010 9:54 UTC www.aboutdomains.com [Source type: Reference]

.ICANN publishes the complete list of TLD registries and domain name registrars.^ Can I change registrars after registering a domain name?
  • ICANN | FAQs 19 January 2010 9:54 UTC www.icann.org [Source type: FILTERED WITH BAYES]

^ National Domain Name Registry, et.
  • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

^ List of TLD domains Related posts .
  • Get Creative With Your Domain Name - Smashing Magazine 19 January 2010 18:018 UTC www.smashingmagazine.com [Source type: FILTERED WITH BAYES]

.Registrant information associated with domain names is maintained in an online database accessible with the WHOIS service.^ Domain Name Registration - 101register.biz .
  • Domain name World Wide - All Whois Server 19 January 2010 9:54 UTC 0domainresources.org [Source type: Academic]

^ In the Shared Registration System model, registrars are responsible for maintaining Whois domain name contact information.
  • ICANN | FAQs 19 January 2010 9:54 UTC www.icann.org [Source type: FILTERED WITH BAYES]

^ The Domain Name System is basically a database of host information.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.For most of the more than 240 country code top-level domains (ccTLDs), the domain registries maintain the WHOIS (Registrant, name servers, expiration dates, etc.^ The other type of TLD is the ccTLD (country code top level domains) which are assigned to all countries and their dependencies.
  • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

^ Registrations in the .name top-level domain must constitute an individual’s “Personal Name”.

^ Explains the naming scheme for top level domains.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

) information. For instance, DENIC, Germany NIC, holds the DE domain data. Since about 2001, most gTLD registries have adopted this so-called thick registry approach, i.e. keeping the WHOIS data in central registries instead of registrar databases.
.For COM and NET domain names, a thin registry model is used: the domain registry (e.g.^ Domain Names by 101domain.com .
  • Domain name World Wide - All Whois Server 19 January 2010 9:54 UTC 0domainresources.org [Source type: Academic]

^ National Domain Name Registry, et.
  • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

^ Free Domain Name -101Freedomains.com .
  • Domain name World Wide - All Whois Server 19 January 2010 9:54 UTC 0domainresources.org [Source type: Academic]

.VeriSign) holds basic WHOIS (registrar and name servers, etc.^ The business or registrar responsible for a domain name’s server and keeping their web site “live.” .
  • Domain Name Glossary - Complete Domain Name Glossary on the Domain Indusry - By Dnforum.com 19 January 2010 18:018 UTC www.dnforum.com [Source type: Reference]

^ In particular, the system was designed so that the name space did not have to be organized along the lines of network boundaries, name servers, etc.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ All the other name servers for a zone basically maintain copies of the primary server’s database for the zone.

) data. .One can find the detailed WHOIS (registrant, name servers, expiry dates, etc.^ Slave name servers are important because it's a good idea to set up more than one name server for any given zone.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ If it does not find that particular domain name, it refers the query to one of the root servers.
  • Internet Domain Names Privatization Competition And Freedom Of Expression 19 January 2010 9:54 UTC www.cato.org [Source type: FILTERED WITH BAYES]

^ Because any one name server only knows about part of the overall domain name space, an inverse query is never guaranteed to return an answer.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

) at the registrars.
.Some domain name registries, often called network information centers (NIC), also function as registrars to end-users.^ National Domain Name Registry, et.
  • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

^ A subdomain's domain name ends with the domain name of its parent domain.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ In the case of a “.cn” registration, the following terms and conditions shall apply: “Registry” means the China Internet Network Information Center, which is the authority responsible for the administration of the national top-level domain of the People’s Republic of China and the Chinese domain name system; “Registry Gateway” means the service provided by the Registry Operator that facilitates the registration of .cn domain names by registrars operating outside of the People’s Republic of China; “Registry Operator“ means Neustar, Inc., the company authorized to facilitate the registration of .cn domain names by registrars operating outside of the People’s Republic of China.

.The major generic top-level domain registries, such as for the COM, NET, ORG, INFO domains and others, use a registry-registrar model consisting of hundreds of domain name registrars (see lists at ICANN or VeriSign).^ Explains the naming scheme for top level domains.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ (In fact, most of the root name servers are authoritative for the generic top-level domains.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ National Domain Name Registry, et.
  • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

.In this method of management, the registry only manages the domain name database and the relationship with the registrars.^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ National Domain Name Registry, et.
  • Domain Name Handbook: Domain Name System in Court 19 January 2010 9:54 UTC www.domainhandbook.com [Source type: FILTERED WITH BAYES]

^ The registrar has a contractual relationship with the registry.
  • The Domain Name System: Where do we go from Here? 19 January 2010 9:54 UTC commdocs.house.gov [Source type: Original source]

.The registrants (users of a domain name) are customers of the registrar, in some cases through additional layers of resellers.^ In the event You are purchasing a domain name on behalf of a third party, You agree to inform any customer of Yours, who may be acquiring a domain name through You using Go Daddy's registration services, that they are in fact registering their domain name through Go Daddy and that Go Daddy is an accredited registrar with ICANN. You agree not to represent that You are an ICANN accredited registrar or that You are in any way providing superior access to the ICANN Domain Name Registry.

^ Not only can they give you data about zones for which they're authoritative, they can also search through the domain name space to find data for which they're not authoritative.
  • DNS and BIND, 3rd Edition -- Sample Chapter 19 January 2010 9:54 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ When a user needs to type a domain name, the length of each label is omitted and the labels are separated by dots ("."
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

Internet standards

.The Domain Name System is defined by Request for Comments (RFC) documents published by the Internet Engineering Task Force (Internet standards).^ III. The management of domain name system .
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

^ Without the Domain Name System, the Internet cannot be functional.
  • The Domain Name System: Where do we go from Here? 19 January 2010 9:54 UTC commdocs.house.gov [Source type: Original source]

^ However, it is worthy noting that the internationalization of the domain name system must be accomplished through standards that are open, non-proprietary, and fully compatible with the Internet's existing end-to-end model and that preserve globally unique naming in a universally resolvable public name space.
  • Internet Law Article: Legal Issues on Domain Name: A World Wide Watch 19 January 2010 9:54 UTC www.law-bridge.net [Source type: FILTERED WITH BAYES]

.The following is a list of RFCs that define the DNS protocol.^ Defines DNS Type AAAA. Obsoletes: RFC 1886 , RFC 3152 .
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

^ Following the owner, we list the TTL, type, and class of the RR. Class and type use the mnemonics defined above, and TTL is an integer before the type field.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

^ RFC 3425 ] Obsoleting IQUERY. Defines DNS opcode 1 (IQUERY) as obsolete.
  • Protocol: DNS ( Domain Name System ) 19 January 2010 9:54 UTC www.protocolbase.net [Source type: Reference]

  • RFC 920, Domain Requirements - Specified original top-level domains
  • RFC 1032, Domain Administrators Guide
  • RFC 1033, Domain Administrators Operations Guide
  • RFC 1034, Domain Names - Concepts and Facilities
  • RFC 1035, Domain Names - Implementation and Specification
  • RFC 1101, DNS Encodings of Network Names and Other Types
  • RFC 1123, Requirements for Internet Hosts—Application and Support
  • RFC 1178, Choosing a Name for Your Computer (FYI 5)
  • RFC 1183, New DNS RR Definitions
  • RFC 1591, Domain Name System Structure and Delegation (Informational)
  • RFC 1912, Common DNS Operational and Configuration Errors
  • RFC 1995, Incremental Zone Transfer in DNS
  • RFC 1996, A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)
  • RFC 2100, The Naming of Hosts (Informational)
  • RFC 2136, Dynamic Updates in the domain name system (DNS UPDATE)
  • RFC 2181, Clarifications to the DNS Specification
  • RFC 2182, Selection and Operation of Secondary DNS Servers
  • RFC 2308, Negative Caching of DNS Queries (DNS NCACHE)
  • RFC 2317, Classless IN-ADDR.ARPA delegation (BCP 20)
  • RFC 2671, Extension Mechanisms for DNS (EDNS0)
  • RFC 2672, Non-Terminal DNS Name Redirection
  • RFC 2845, Secret Key Transaction Authentication for DNS (TSIG)
  • RFC 3225, Indicating Resolver Support of DNSSEC
  • RFC 3226, DNSSEC and IPv6 A6 aware server/resolver message size requirements
  • RFC 3597, Handling of Unknown DNS Resource Record (RR) Types
  • RFC 3696, Application Techniques for Checking and Transformation of Names (Informational)
  • RFC 4343, Domain Name System (DNS) Case Insensitivity Clarification
  • RFC 4592, The Role of Wildcards in the Domain Name System
  • RFC 4635, HMAC SHA TSIG Algorithm Identifiers
  • RFC 4892, Requirements for a Mechanism Identifying a Name Server Instance (Informational)
  • RFC 5001, DNS Name Server Identifier (NSID) Option
  • RFC 5395, Domain Name System (DNS) IANA Considerations (BCP 42)
  • RFC 5452, Measures for Making DNS More Resilient against Forged Answers'
  • RFC 5625, DNS Proxy Implementation Guidelines (BCP 152)

Security

  • RFC 4033, DNS Security Introduction and Requirements
  • RFC 4034, Resource Records for the DNS Security Extensions
  • RFC 4035, Protocol Modifications for the DNS Security Extensions
  • RFC 4509, Use of SHA-256 in DNSSEC Delegation Signer (DS) Resource Records
  • RFC 4470, Minimally Covering NSEC Records and DNSSEC On-line Signing
  • RFC 5011, Automated Updates of DNS Security (DNSSEC) Trust Anchors
  • RFC 5155, DNS Security (DNSSEC) Hashed Authenticated Denial of Existence
  • RFC 5702, Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC

See also

References

  1. ^ Mockapetris, Paul (2004-01-02). "Letting DNS Loose". CircleID. http://www.circleid.com/posts/letting_dns_loose/. 
  2. ^ a b c RFC 1034, Domain Names - Concepts and Facilities, P. Mockapetris, The Internet Society (November 1987)
  3. ^ RFC 781, Internet Protocol - DARPA Internet Program Protocol Specification, Information Sciences Institute, J. Postel (Ed.), The Internet Society (September 1981)
  4. ^ a b c d RFC 1035, Domain Names - Implementation and Specification, P. Mockapetris, The Internet Society (November 1987)
  5. ^ RFC 3467 - Role of the Domain Name System (DNS)
  6. ^ Cricket Liu, Paul Albitz. "DNS & BIND". O'Reilly (shown via Google Books). http://books.google.co.uk/books?id=zkZN52WhG8sC&pg=PA3&lpg=PA3&dq=sri+HOSTS.TXT&source=web&ots=wuZ79E-zJ2&sig=btF0Z2nclOnX_UgNj7a1f5S7Uqg&hl=en. Retrieved 2008-04-29. 
  7. ^ DNS Server Survey
  8. ^ What is the maximum length of a domain name? on the IETF DNSOP working group mailing list. On the wire and in the internal binary storage format it can be at most 255 octets as per RFC 1034 section 3.1. For an all-ASCII hostname, this can be represented in traditional dot notation as 253 characters.
  9. ^ "Name Server definition at techterms.com". http://www.techterms.com/definition/nameserver. 
  10. ^ "Providers ignoring DNS TTL ?". Slashdot. 2005. http://ask.slashdot.org/article.pl?sid=05/04/18/198259. Retrieved 2009-01-03. 
  11. ^ "How Internet Explorer uses the cache for DNS host entries". Microsoft. 2004. http://support.microsoft.com/default.aspx?scid=KB;en-us;263558. Retrieved 2006-03-07. 
  12. ^ Mockapetris, P (November 1987). "RFC 1035: Domain Names - Implementation and Specification". http://www.ietf.org/rfc/rfc1035.txt. 
  13. ^ a b RFC 4592, The Role of Wildcards in the Domain Name System, E. Lewis (July 2006)

External links


The Domain Name System (DNS) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.

An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the domain name www.example.com translates to the addresses 192.0.32.10 (IPv4) and 2620:0:2d0:200::10 (IPv6).

The Domain Name System makes it possible to assign domain names to groups of Internet resources and users in a meaningful way, independent of each entity's physical location. Because of this, World Wide Web (WWW) hyperlinks and Internet contact information can remain consistent and constant even if the current Internet routing arrangements change or the participant uses a mobile device. Internet domain names are easier to remember than IP addresses such as 208.77.188.166 (IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6). Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and e-mail addresses without having to know how the computer actually locates them.

The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains. This mechanism has made the DNS distributed and fault tolerant and has helped avoid the need for a single central register to be continually consulted and updated.

In general, the Domain Name System also stores other types of information, such as the list of mail servers that accept email for a given Internet domain. By providing a worldwide, distributed keyword-based redirection service, the Domain Name System is an essential component of the functionality of the Internet.

Other identifiers such as RFID tags, UPC codes, International characters in email addresses and host names, and a variety of other identifiers could all potentially utilize DNS.[1]

The Domain Name System also defines the technical underpinnings of the functionality of this database service. For this purpose it defines the DNS protocol, a detailed specification of the data structures and communication exchanges used in DNS, as part of the Internet Protocol Suite.

Internet Protocol Suite
Application Layer

BGP

  1. REDIRECT template:· DHCP
  2. REDIRECT template:· DNS
  3. REDIRECT template:· FTP
  4. REDIRECT template:· HTTP
  5. REDIRECT template:· IMAP
  6. REDIRECT template:· IRC
  7. REDIRECT template:· LDAP
  8. REDIRECT template:· MGCP
  9. REDIRECT template:· NNTP
  10. REDIRECT template:· NTP
  11. REDIRECT template:· POP
  12. REDIRECT template:· RIP
  13. REDIRECT template:· RPC
  14. REDIRECT template:· RTP
  15. REDIRECT template:· SIP
  16. REDIRECT template:· SMTP
  17. REDIRECT template:· SNMP
  18. REDIRECT template:· SSH
  19. REDIRECT template:· Telnet
  20. REDIRECT template:· TLS/SSL
  21. REDIRECT template:· XMPPTemplate:·
(more)
Transport Layer

TCP

  1. REDIRECT template:· UDP
  2. REDIRECT template:· DCCP
  3. REDIRECT template:· SCTP
  4. REDIRECT template:· RSVP
  5. REDIRECT template:· ECNTemplate:·
(more)
Internet Layer

IP (IPv4, IPv6)

  1. REDIRECT template:· ICMP
  2. REDIRECT template:· ICMPv6
  3. REDIRECT template:· IGMP
  4. REDIRECT template:· IPsecTemplate:·
(more)
Link Layer

ARP/InARP

  1. REDIRECT template:· NDP
  2. REDIRECT template:· OSPF
  3. REDIRECT template:· Tunnels (L2TP)
  4. REDIRECT template:· PPP
  5. REDIRECT template:· Media Access Control (Ethernet, DSL, ISDN, FDDI)Template:· (more)

Contents

Overview

The Internet maintains two principal namespaces, the domain name hierarchy[2] and the Internet Protocol (IP) address system.[3] The Domain Name System maintains the domain namespace and provides translation services between these two namespaces. Internet name servers and a communications protocol implement the Domain Name System.[4] A DNS name server is a server that stores the DNS records, such as address (A) records, name server (NS) records, and mail exchanger (MX) records for a domain name (see also List of DNS record types) and responds with answers to queries against its database.

History

The practice of using a name as a humanly more meaningful abstraction of a host's numerical address on the network dates back to the ARPANET era. Before the DNS was invented in 1983, each computer on the network retrieved a file called HOSTS.TXT from a computer at SRI (now SRI International).[5][6] The HOSTS.TXT file mapped names to numerical addresses. A hosts file still exists on most modern operating systems, either by default or through explicit configuration. Many operating systems use name resolution logic that allows the administrator to configure selection priorities for available name resolution methods.

The rapid growth of the network required a scalable system that recorded a change in a host's address in one place only. Other hosts would learn about the change dynamically through a notification system, thus completing a globally accessible network of all hosts' names and their associated IP addresses.

At the request of Jon Postel, Paul Mockapetris invented the Domain Name System in 1983 and wrote the first implementation. The original specifications appeared in RFC 882 and RFC 883 which were superseded in November 1987 by RFC 1034[2] and RFC 1035[4]. Several additional Request for Comments have proposed various extensions to the core DNS protocols.

In 1984, four Berkeley students—Douglas Terry, Mark Painter, David Riggle and Songnian Zhou—wrote the first UNIX implementation, called The Berkeley Internet Name Domain (BIND) Server.[7] In 1985, Kevin Dunlap of DEC significantly re-wrote the DNS implementation. Mike Karels, Phil Almquist and Paul Vixie have maintained BIND since then. BIND was ported to the Windows NT platform in the early 1990s.

BIND was widely distributed, especially on Unix systems, and is the dominant DNS software in use on the Internet.[8] With the heavy use and resulting scrutiny of its open-source code, as well as increasingly more sophisticated attack methods, many security flaws were discovered in BIND. This contributed to the development of a number of alternative name server and resolver programs. BIND itself was re-written from scratch in version 9, which has a security record comparable to other modern Internet software.

The DNS protocol was developed and defined in the early 1980s and published by the Internet Engineering Task Force.

Structure

Domain name space

The domain name space consists of a tree of domain names. Each node or leaf in the tree has zero or more resource records, which hold information associated with the domain name. The tree sub-divides into zones beginning at the root zone. A DNS zone consists of a collection of connected nodes authoritatively served by an authoritative nameserver. (A single nameserver can host several zones.)

Administrative responsibility over any zone may be divided, thereby creating additional zones. Authority is said to be delegated for a portion of the old space, usually in form of sub-domains, to another nameserver and administrative entity. The old zone ceases to be authoritative for the new zone.

Domain name formulation

The definitive descriptions of the rules for forming domain names appear in RFC 1035, RFC 1123, and RFC 2181. A domain name consists of one or more parts, technically called labels, that are conventionally concatenated, and delimited by dots, such as example.com.

  • The right-most label conveys the top-level domain; for example, the domain name www.example.com belongs to the top-level domain com.
  • The hierarchy of domains descends from right to left; each label to the left specifies a subdivision, or subdomain of the domain to the right. For example: the label example specifies a subdomain of the com domain, and www is a sub domain of example.com. This tree of subdivisions may consist of 127 levels.
  • Each label may contain up to 63 characters. The full domain name may not exceed a total length of 253 characters.[9] In practice, some domain registries may have shorter limits.
  • DNS names may technically consist of any character representable in an octet. However, the allowed formulation of domain names in the DNS root zone, and most other sub domains, uses a preferred format and character set. The characters allowed in a label are a subset of the ASCII character set, and includes the characters a through z, A through Z, digits 0 through 9, and the hyphen. This rule is known as the LDH rule (letters, digits, hyphen). Domain names are interpreted in case-independent manner. Labels may not start or end with a hyphen.[10]
  • A hostname is a domain name that has at least one IP address associated. For example, the domain names www.example.com and example.com are also hostnames, whereas the com domain is not.

Internationalized domain names

The permitted character set of the DNS prevented the representation of names and words of many languages in their native alphabets or scripts. ICANN has approved the Internationalizing Domain Names in Applications (IDNA) system, which maps Unicode strings into the valid DNS character set using Punycode. In 2009 ICANN approved the installation of IDN country code top-level domains. In addition, many registries of the existing TLDs have adopted IDNA.

Name servers

The Domain Name System is maintained by a distributed database system, which uses the client-server model. The nodes of this database are the name servers. Each domain has at least one authoritative DNS server that publishes information about that domain and the name servers of any domains subordinate to it. The top of the hierarchy is served by the root nameservers, the servers to query when looking up (resolving) a top-level domain name (TLD).

Authoritative name server

An authoritative name server is a name server that gives answers that have been configured by an original source, for example, the domain administrator or by dynamic DNS methods, in contrast to answers that were obtained via a regular DNS query to another name server. An authoritative-only name server only returns answers to queries about domain names that have been specifically configured by the administrator.

An authoritative name server can either be a master server or a slave server. A master server is a server that stores the original (master) copies of all zone records. A slave server uses an automatic updating mechanism of the DNS protocol in communication with its master to maintain an identical copy of the master records.

Every DNS zone must be assigned a set of authoritative name servers that are installed in NS records in the parent zone.

When domain names are registered with a domain name registrar their installation at the domain registry of a top level domain requires the assignment of a primary name server and at least one secondary name server. The requirement of multiple name servers aims to make the domain still functional even if one name server becomes inaccessible or inoperable.[11] The designation of a primary name server is solely determined by the priority given to the domain name registrar. For this purpose generally only the fully qualified domain name of the name server is required, unless the servers are contained in the registered domain, in which case the corresponding IP address is needed as well.

Primary name servers are often master name servers, while secondary name server may be implemented as slave servers.

An authoritative server indicates its status of supplying definitive answers, deemed authoritative, by setting a software flag (a protocol structure bit), called the Authoritative Answer (AA) bit in its responses.[4] This flag is usually reproduced prominently in the output of DNS administration query tools (such as dig) to indicate that the responding name server is an authority for the domain name in question.[4]

Recursive and caching name server

In principle, authoritative name servers are sufficient for the operation of the Internet. However, with only authoritative name servers operating, every DNS query must start with recursive queries at the root zone of the Domain Name System and each user system must implement resolver software capable of recursive operation.

To improve efficiency, reduce DNS traffic across the Internet, and increase performance in end-user applications, the Domain Name System supports DNS cache servers which store DNS query results for a period of time determined in the configuration (time-to-live) of the domain name record in question. Typically, such caching DNS servers, also called DNS caches, also implement the recursive algorithm necessary to resolve a given name starting with the DNS root through to the authoritative name servers of the queried domain. With this function implemented in the name server, user applications gain efficiency in design and operation.

The combination of DNS caching and recursive functions in a name server is not mandatory, the functions can be implemented independently in servers for special purposes.

Internet service providers typically provide recursive and caching name servers for their customers. In addition, many home networking routers implement DNS caches and recursors to improve efficiency in the local network.

DNS resolvers

The client-side of the DNS is called a DNS resolver. It is responsible for initiating and sequencing the queries that ultimately lead to a full resolution (translation) of the resource sought, e.g., translation of a domain name into an IP address.

A DNS query may be either a non-recursive query or a recursive query:

  • A non-recursive query is one in which the DNS server provides a record for a domain for which it is authoritative itself, or it provides a partial result without querying other servers.
  • A recursive query is one for which the DNS server will fully answer the query (or give an error) by querying other name servers as needed. DNS servers are not required to support recursive queries.

The resolver, or another DNS server acting recursively on behalf of the resolver, negotiates use of recursive service using bits in the query headers.

Resolving usually entails iterating through several name servers to find the needed information. However, some resolvers function simplistically and can communicate only with a single name server. These simple resolvers (called "stub resolvers") rely on a recursive name server to perform the work of finding information for them.

Operation

Address resolution mechanism

Domain name resolvers determine the appropriate domain name servers responsible for the domain name in question by a sequence of queries starting with the right-most (top-level) domain label.

The process entails:

  1. A system that needs to use the DNS is configured with the known addresses of the root servers. This is often stored in a file of root hints, which are updated periodically by an administrator from a reliable source.
  2. Query one of the root servers to find the server authoritative for the top-level domain.
  3. Query the obtained TLD DNS server for the address of a DNS server authoritative for the second-level domain.
  4. Repeating the previous step to process each domain name label in sequence, until the final step which would, rather than generating the address of the next DNS server, return the IP address of the host sought.

The diagram illustrates this process for the host www.wikipedia.org.

The mechanism in this simple form would place a large operating burden on the root servers, with every search for an address starting by querying one of them. Being as critical as they are to the overall function of the system, such heavy use would create an insurmountable bottleneck for trillions of queries placed every day. In practice caching is used in DNS servers to overcome this problem, and as a result, root nameservers actually are involved with very little of the total traffic.

Circular dependencies and glue records

Name servers in delegations are identified by name, rather than by IP address. This means that a resolving name server must issue another DNS request to find out the IP address of the server to which it has been referred. If the name given in the delegation is a subdomain of the domain for which the delegation is being provided, there is a circular dependency. In this case the nameserver providing the delegation must also provide one or more IP addresses for the authoritative nameserver mentioned in the delegation. This information is called glue. The delegating name server provides this glue in the form of records in the additional section of the DNS response, and provides the delegation in the answer section of the response.

For example, consider the domain example.org. Assume that the authoritative name server for example.org is ns1.example.org. A computer trying to resolve www.example.org will first have to resolve ns1.example.org. Since ns1 is also under example.org, resolving ns1.example.org requires resolving example.org—a circular dependency. To break the dependency, the nameserver for the org top level domain includes glue along with the delegation for example.org. The glue records are A and/or AAAA records that provide IP addresses for ns1.example.org. The resolver uses one or more of these IP addresses to satisfy the circular dependency, which allows it to communicate with ns1.example.org and finish resolving the DNS query.

Record caching

Because of the large volume of requests generated in the DNS for the public Internet, the designers wished to provide a mechanism to reduce the load on individual DNS servers. To this end, the DNS resolution process allows for caching of records for a period of time after an answer. This entails the local recording and subsequent consultation of the copy instead of initiating a new request upstream. The time for which a resolver caches a DNS response is determined by a value called the time to live (TTL) associated with every record. The TTL is set by the administrator of the DNS server handing out the authoritative response. The period of validity may vary from just seconds to days or even weeks.

As a noteworthy consequence of this distributed and caching architecture, changes to DNS records do not propagate throughout the network immediately, but require all caches to expire and refresh after the TTL. RFC 1912 conveys basic rules for determining appropriate TTL values.

Some resolvers may override TTL values, as the protocol supports caching for up to 68 years or no caching at all. Negative caching, i.e. the caching of the fact of non-existence of a record, is determined by name servers authoritative for a zone which must include the Start of Authority (SOA) record when reporting no data of the requested type exists. The value of the MINIMUM field of the SOA record and the TTL of the SOA itself is used to establish the TTL for the negative answer.

Reverse lookup

A reverse lookup is a query of the DNS for domain names when the IP address is known. Multiple domain names may be associated with an IP address. The DNS stores IP addresses in the form of domain names as a specially formatted names in pointer (PTR) records within the infrastructure top-level domain arpa. For IPv4, the domain is in-addr.arpa. For IPv6, the reverse lookup domain is ip6.arpa. The IP address is represented as a name in reverse-ordered octet representation for IPv4, and reverse-ordered nibble representation for IPv6.

When performing a reverse lookup, the DNS client converts the address into these formats, and then queries the name for a PTR record following the delegation chain as for any DNS query. For example, the IPv4 address 208.80.152.2 is represented as a DNS name as 2.152.80.208.in-addr.arpa. The DNS resolver begins by querying the root servers, which point to ARIN's servers for the 208.in-addr.arpa zone. From there the Wikimedia servers are assigned for 152.80.208.in-addr.arpa, and the PTR lookup completes by querying the wikimedia nameserver for 2.152.80.208.in-addr.arpa, which results in an authoritative response.

Client lookup

Users generally do not communicate directly with a DNS resolver. Instead DNS resolution takes place transparently in applications programs such as web browsers, e-mail clients, and other Internet applications. When an application makes a request that requires a domain name lookup, such programs send a resolution request to the DNS resolver in the local operating system, which in turn handles the communications required.

The DNS resolver will almost invariably have a cache (see above) containing recent lookups. If the cache can provide the answer to the request, the resolver will return the value in the cache to the program that made the request. If the cache does not contain the answer, the resolver will send the request to one or more designated DNS servers. In the case of most home users, the Internet service provider to which the machine connects will usually supply this DNS server: such a user will either have configured that server's address manually or allowed DHCP to set it; however, where systems administrators have configured systems to use their own DNS servers, their DNS resolvers point to separately maintained nameservers of the organization. In any event, the name server thus queried will follow the process outlined above, until it either successfully finds a result or does not. It then returns its results to the DNS resolver; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request.

Broken resolvers

An additional level of complexity emerges when resolvers violate the rules of the DNS protocol. A number of large ISPs have configured their DNS servers to violate rules (presumably to allow them to run on less-expensive hardware than a fully compliant resolver), such as by disobeying TTLs, or by indicating that a domain name does not exist just because one of its name servers does not respond.[12]

As a final level of complexity, some applications (such as web-browsers) also have their own DNS cache, in order to reduce the use of the DNS resolver library itself. This practice can add extra difficulty when debugging DNS issues, as it obscures the freshness of data, and/or what data comes from which cache. These caches typically use very short caching times—on the order of one minute[citation needed].

Internet Explorer offers a notable exception: versions up to IE 3.x cache DNS records for 24 hours by default. Internet Explorer 4.x and later versions (up to IE 8) decrease the default time out value to half an hour. That value can be changed by modifying corresponding registry keys.[13]

Other applications

The system outlined above provides a somewhat simplified scenario. The Domain Name System includes several other functions:

  • Hostnames and IP addresses do not necessarily match on a one-to-one basis. Many hostnames may correspond to a single IP address: combined with virtual hosting, this allows a single machine to serve many web sites. Alternatively a single hostname may correspond to many IP addresses: this can facilitate fault tolerance and load distribution, and also allows a site to move physical location seamlessly.
  • There are many uses of DNS besides translating names to IP addresses. For instance, Mail transfer agents use DNS to find out where to deliver e-mail for a particular address. The domain to mail exchanger mapping provided by MX records accommodates another layer of fault tolerance and load distribution on top of the name to IP address mapping.
  • E-mail Blacklists: The DNS system is used for efficient storage and distribution of IP addresses of blacklisted e-mail hosts. The usual method is putting the IP address of the subject host into the sub-domain of a higher level domain name, and resolve that name to different records to indicate a positive or a negative. A hypothetical example using blacklist.com,
    • 102.3.4.5 is blacklisted => Creates 5.4.3.102.blacklist.com and resolves to 127.0.0.1
    • 102.3.4.6 is not => 6.4.3.102.blacklist.com is not found, or default to 127.0.0.2
    • E-mail servers can then query blacklist.com through the DNS mechanism to find out if a specific host connecting to them is in the blacklist. Today many of such blacklists, either free or subscription-based, are available mainly for use by email administrators and anti-spam software.
  • Software Updates: many anti-virus and commercial software now use the DNS system to store version numbers of the latest software updates so client computers do not need to connect to the update servers every time. For these types of applications, the cache time of the DNS records are usually shorter.
  • Sender Policy Framework and DomainKeys, instead of creating their own record types, were designed to take advantage of another DNS record type, the TXT record.
  • To provide resilience in the event of computer failure, multiple DNS servers are usually provided for coverage of each domain, and at the top level, thirteen very powerful root servers exist, with additional "copies" of several of them distributed worldwide via Anycast.
  • Dynamic DNS (also referred to as DDNS) provides clients the ability to update their IP address in the DNS after it changes due to mobility, e.g.

Protocol details

DNS primarily uses User Datagram Protocol (UDP) on port number 53 to serve requests.[4] DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server. The Transmission Control Protocol (TCP) is used when the response data size exceeds 512 bytes, or for tasks such as zone transfers. Some operating systems, such as HP-UX, are known to have resolver implementations that use TCP for all queries, even when UDP would suffice.

DNS resource records

A Resource Record (RR) is the basic data element in the domain name system. Each record has a type (A, MX, etc.), an expiration time limit, a class, and some type-specific data. Resource records of the same type define a resource record set. The order of resource records in a set, returned by a resolver to an application, is undefined, but often servers implement round-robin ordering to achieve load balancing. DNSSEC, however, works on complete resource record sets in a canonical order.

When sent over an IP network, all records use the common format specified in RFC 1035 and shown below:

RR (Resource record) fields
Field Description Length (octets)
NAME Name of the node to which this record pertains (variable)
TYPE Type of RR in numeric form (e.g. 15 for MX RRs) 2
CLASS Class code 2
TTL Unsigned time in seconds that RR stays valid (maximum 2147483647) 4
RDLENGTH Length of RDATA field 2
RDATA Additional RR-specific data (variable)

NAME is the fully qualified domain name of the node in the tree. On the wire, the name may be shortened using label compression where ends of domain names mentioned earlier in the packet can be substituted for the end of the current domain name.

TYPE is the record type. It indicates the format of the data and it gives a hint of its intended use. For example, the A record is used to translate from a domain name to an IPv4 address, the NS record lists which name servers can answer lookups on a DNS zone, and the MX record specifies the mail server used to handle mail for a domain specified in an e-mail address (see also List of DNS record types).

RDATA is data of type-specific relevance, such as the IP address for address records, or the priority and hostname for MX records. Well known record types may use label compression in the RDATA field, but "unknown" record types must not (RFC 3597).

The CLASS of a record is set to IN (for Internet) for common DNS records involving Internet hostnames, servers, or IP addresses. In addition, the classes CH (Chaos) and HS (Hesiod) exist. Each class is a completely independent tree with potentially different delegations of DNS zones.

In addition to resource records defined in a zone file, the domain name system also defines several request types that are used only in communication with other DNS nodes (on the wire), such as when performing zone transfers (AXFR/IXFR) or for EDNS (OPT).

Wildcard DNS records

The domain name system supports wildcard domain names which are names that start with the asterisk label, '*', e.g., *.example.[2][14] DNS records belonging to wildcard domain names specify rules for generating resource records within a single DNS zone by substituting whole labels with matching components of the query name, including any specified descendants. For example, in the DNS zone x.example, the following configuration specifies that all subdomains (including subdomains of subdomains) of x.example use the mail exchanger a.x.example. The records for a.x.example are needed to specify the mail exchanger. As this has the result of excluding this domain name and its subdomains from the wildcard matches, all subdomains of a.x.example must be defined in a separate wildcard statement.

X.EXAMPLE.       MX   10 A.X.EXAMPLE.
*.X.EXAMPLE.     MX   10 A.X.EXAMPLE.
*.A.X.EXAMPLE.   MX   10 A.X.EXAMPLE.
A.X.EXAMPLE.     MX   10 A.X.EXAMPLE.
A.X.EXAMPLE.     AAAA 2001:db8::1

The role of wildcard records was refined in RFC 4592, because the original definition in RFC 1034 was incomplete and resulted in misinterpretations by implementers.[14]

Protocol extensions

The original DNS protocol had limited provisions for extension with new features. In 1999, Paul Vixie published in RFC 2671 an extension mechanism, called Extension mechanisms for DNS (EDNS) that introduced optional protocol elements without increasing overhead when not in use. This was accomplished through the OPT pseudo-resource record that only exists in wire transmissions of the protocol, but not in any zone files. Initial extensions were also suggested (EDNS0), such as increasing the DNS message size in UDP datagrams.

Dynamic zone updates

Dynamic DNS updates use the UPDATE DNS opcode to add or remove resource records dynamically from a zone data base maintained on an authoritative DNS server. The feature is described in RFC 2136. This facility is useful to register network clients into the DNS when they boot or become otherwise available on the network. Since a booting client may be assigned a different IP address each time from a DHCP server, it is not possible to provide static DNS assignments for such clients.

Security issues

DNS was not originally designed with security in mind, and thus has a number of security issues.

One class of vulnerabilities is DNS cache poisoning, which tricks a DNS server into believing it has received authentic information when, in reality, it has not.

DNS responses are traditionally not cryptographically signed, leading to many attack possibilities; the Domain Name System Security Extensions (DNSSEC) modifies DNS to add support for cryptographically signed responses. There are various extensions to support securing zone transfer information as well.

Even with encryption, a DNS server could become compromised by a virus (or for that matter a disgruntled employee) that would cause IP addresses of that server to be redirected to a malicious address with a long TTL. This could have far-reaching impact to potentially millions of Internet users if busy DNS servers cache the bad IP data. This would require manual purging of all affected DNS caches as required by the long TTL (up to 68 years).

Some domain names can spoof other, similar-looking domain names. For example, "paypal.com" and "paypa1.com" are different names, yet users may be unable to tell the difference when the user's typeface (font) does not clearly differentiate the letter l and the numeral 1. This problem is more serious in systems that support internationalized domain names, since many character codes in ISO 10646, may appear identical on typical computer screens. This vulnerability is often exploited in phishing.[citation needed]

Techniques such as forward-confirmed reverse DNS can also be used to help validate DNS results.

Domain name registration

The right to use a domain name is delegated by domain name registrars which are accredited by the Internet Corporation for Assigned Names and Numbers (ICANN), the organization charged with overseeing the name and number systems of the Internet. In addition to ICANN, each top-level domain (TLD) is maintained and serviced technically by an administrative organization, operating a registry. A registry is responsible for maintaining the database of names registered within the TLD it administers. The registry receives registration information from each domain name registrar authorized to assign names in the corresponding TLD and publishes the information using a special service, the whois protocol.

ICANN publishes the complete list of TLD registries and domain name registrars. Registrant information associated with domain names is maintained in an online database accessible with the WHOIS service. For most of the more than 240 country code top-level domains (ccTLDs), the domain registries maintain the WHOIS (Registrant, name servers, expiration dates, etc.) information. For instance, DENIC, Germany NIC, holds the DE domain data. Since about 2001, most gTLD registries have adopted this so-called thick registry approach, i.e. keeping the WHOIS data in central registries instead of registrar databases.

For COM and NET domain names, a thin registry model is used: the domain registry (e.g. VeriSign) holds basic WHOIS (registrar and name servers, etc.) data. One can find the detailed WHOIS (registrant, name servers, expiry dates, etc.) at the registrars.

Some domain name registries, often called network information centers (NIC), also function as registrars to end-users. The major generic top-level domain registries, such as for the COM, NET, ORG, INFO domains, use a registry-registrar model consisting of many domain name registrars[15][16] In this method of management, the registry only manages the domain name database and the relationship with the registrars. The registrants (users of a domain name) are customers of the registrar, in some cases through additional layers of resellers.

Internet standards

The Domain Name System is defined by Request for Comments (RFC) documents published by the Internet Engineering Task Force (Internet standards). The following is a list of RFCs that define the DNS protocol.

  • RFC 920, Domain Requirements – Specified original top-level domains
  • RFC 1032, Domain Administrators Guide
  • RFC 1033, Domain Administrators Operations Guide
  • RFC 1034, Domain Names - Concepts and Facilities
  • RFC 1035, Domain Names - Implementation and Specification
  • RFC 1101, DNS Encodings of Network Names and Other Types
  • RFC 1123, Requirements for Internet Hosts—Application and Support
  • RFC 1178, Choosing a Name for Your Computer (FYI 5)
  • RFC 1183, New DNS RR Definitions
  • RFC 1591, Domain Name System Structure and Delegation (Informational)
  • RFC 1912, Common DNS Operational and Configuration Errors
  • RFC 1995, Incremental Zone Transfer in DNS
  • RFC 1996, A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)
  • RFC 2100, The Naming of Hosts (Informational)
  • RFC 2136, Dynamic Updates in the domain name system (DNS UPDATE)
  • RFC 2181, Clarifications to the DNS Specification
  • RFC 2182, Selection and Operation of Secondary DNS Servers
  • RFC 2308, Negative Caching of DNS Queries (DNS NCACHE)
  • RFC 2317, Classless IN-ADDR.ARPA delegation (BCP 20)
  • RFC 2671, Extension Mechanisms for DNS (EDNS0)
  • RFC 2672, Non-Terminal DNS Name Redirection
  • RFC 2845, Secret Key Transaction Authentication for DNS (TSIG)
  • RFC 3225, Indicating Resolver Support of DNSSEC
  • RFC 3226, DNSSEC and IPv6 A6 aware server/resolver message size requirements
  • RFC 3597, Handling of Unknown DNS Resource Record (RR) Types
  • RFC 3696, Application Techniques for Checking and Transformation of Names (Informational)
  • RFC 4343, Domain Name System (DNS) Case Insensitivity Clarification
  • RFC 4592, The Role of Wildcards in the Domain Name System
  • RFC 4635, HMAC SHA TSIG Algorithm Identifiers
  • RFC 4892, Requirements for a Mechanism Identifying a Name Server Instance (Informational)
  • RFC 5001, DNS Name Server Identifier (NSID) Option
  • RFC 5395, Domain Name System (DNS) IANA Considerations (BCP 42)
  • RFC 5452, Measures for Making DNS More Resilient against Forged Answers
  • RFC 5625, DNS Proxy Implementation Guidelines (BCP 152)

Security

  • RFC 4033, DNS Security Introduction and Requirements
  • RFC 4034, Resource Records for the DNS Security Extensions
  • RFC 4035, Protocol Modifications for the DNS Security Extensions
  • RFC 4509, Use of SHA-256 in DNSSEC Delegation Signer (DS) Resource Records
  • RFC 4470, Minimally Covering NSEC Records and DNSSEC On-line Signing
  • RFC 5011, Automated Updates of DNS Security (DNSSEC) Trust Anchors
  • RFC 5155, DNS Security (DNSSEC) Hashed Authenticated Denial of Existence
  • RFC 5702, Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC

See also

File:Internet map 1024.jpg Computer Science portal

References

  1. ^ Mockapetris, Paul (2004-01-02). "Letting DNS Loose". CircleID. http://www.circleid.com/posts/letting_dns_loose/. 
  2. ^ a b c RFC 1034, Domain Names - Concepts and Facilities, P. Mockapetris, The Internet Society (November 1987)
  3. ^ RFC 781, Internet Protocol - DARPA Internet Program Protocol Specification, Information Sciences Institute, J. Postel (Ed.), The Internet Society (September 1981)
  4. ^ a b c d e RFC 1035, Domain Names - Implementation and Specification, P. Mockapetris, The Internet Society (November 1987)
  5. ^ RFC 3467, Role of the Domain Name System (DNS), J.C. Klensin, J. Klensin (February 2003)
  6. ^ Cricket Liu, Paul Albitz (2006). DNS and BIND (5th ed.). O'Reilly. p. 3. http://oreilly.com/catalog/9780596100575. 
  7. ^ Douglas Brian Terry, Mark Painter, David W. Riggle and Songnian Zhou, The Berkeley Internet Name Domain Server, Proceedings USENIX Summer Conference, Salt Lake City, Utah, June 1984, pages 23–31.
  8. ^ "DNS Server Survey". http://mydns.bboy.net/survey/. 
  9. ^ Stuart Cheshire. "RFC 2181: What is the maximum length of a domain name?". http://www.ops.ietf.org/lists/namedroppers/namedroppers.2003/msg00964.html. "[...] the maximum length of a domain name is 255 octets. [...] but what is included in that count? [...] There's a discrepancy of *two* between RFC 1034 and RFC 2181."  This is a thread on the IETF DNSOP working group mailing list. The outcome is that on the wire and in the internal binary storage format it can be at most 255 octets as per RFC 1034 section 3.1. For an all-ASCII hostname, this can be represented in traditional dot notation as 253 characters.
  10. ^ RFC 36796, Application Techniques for Checking and Transformation of Names, J.C. Klensin, J. Klensin
  11. ^ "Name Server definition at techterms.com". http://www.techterms.com/definition/nameserver. 
  12. ^ "Providers ignoring DNS TTL ?". Slashdot. 2005. http://ask.slashdot.org/article.pl?sid=05/04/18/198259. Retrieved 2009-01-03. 
  13. ^ "How Internet Explorer uses the cache for DNS host entries". Microsoft Corporation. 2004. http://support.microsoft.com/default.aspx?scid=KB;en-us;263558. Retrieved 2010-07-25. 
  14. ^ a b RFC 4592, The Role of Wildcards in the Domain Name System, E. Lewis (July 2006)
  15. ^ ICANN accredited registrars
  16. ^ VeriSign COM and NET registry

External links


Study guide

Up to date as of January 14, 2010

From Wikiversity

.The Domain Name System is a hierarchical distributed database system that serves to translate string queries (such as http://www.wikipedia.org) into an IP address which a host may connect to.^ It may not know the IP address for the requested domain but it can provide an IP address for a name server that knows more.
  • Domain Name System (DNS) - Above.com Domain Blog 19 January 2010 9:54 UTC www.above.com [Source type: General]

^ DNS is what's responsible for translating domain names in IP addresses - this process is called resolving.
  • Triple.com - Articles: DNS (Domain Name System) History 19 January 2010 9:54 UTC www.triple.com [Source type: General]

^ The Domain Name System ( DNS ) is a system, which contains domain names; it translates all hostnames into the IP addresses that is necessary for delivering information.
  • ELDEV: Domain Registration 19 January 2010 18:018 UTC www.eldev.com [Source type: Reference]

.DNS is also utilised in email, where email address lookups are performed, and the relevant IP addresses returned.^ The mcslp.com DNS server returns the IP address to the DNS server.
  • Systems Administration Toolkit: Understanding DNS 19 January 2010 18:018 UTC www.ibm.com [Source type: General]

^ Email to an IP address .
  • SamSpade.org 19 January 2010 18:018 UTC samspade.org [Source type: General]

^ The numeric IP addresses of the DNS servers are .
  • InfoTech at K-State: Domain Name System (DNS) 19 January 2010 9:54 UTC www.k-state.edu [Source type: Reference]

.To perform a lookup, a program known as a resolver is passed the string as a parameter.^ A client program, such as a web browser, will contact a resolver with a request for a lookup, for example to find the numeric IP address equivalent to a given Internet name.
  • 3. Domain Name System (DNS) 19 January 2010 9:54 UTC www.ja.net [Source type: FILTERED WITH BAYES]

^ A reverse lookup zone allows you to perform address-to-name resolution (also known as reverse lookup queries).
  • Domain Name System (DNS) – Part III Creating and Managing DNS Zones in Microsoft Windows | NetworkWorld.com Community 19 January 2010 9:54 UTC www.networkworld.com [Source type: General]

^ When the resolver performs the indicated function, it usually has one of the following results to pass back to the client: - One or more RRs giving the requested data.
  • Safenames : Regulations - MC, MC, , Global Domain Name Registrations, Virtual Hosting, Country Specific Domain Names 19 January 2010 9:54 UTC www.safenames.net [Source type: Reference]

.The resolver then sends a UDP packet to the local DNS server, which returns the IP address mapped to the string.^ The local DNS recursor then asks that DNS server (i.e.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ The target’s local DNS server returns the IP address of the actual resource to the local DNS server that handles the requesting browser.
  • Domain Name System - Hill2dot0 19 January 2010 9:54 UTC www.hill2dot0.com [Source type: Reference]

^ The .sun.com server then returns the IP address of www.sun.com to the requesting DNS server.
  • BigAdmin Feature Article: Introduction to the Domain Name System 19 January 2010 9:54 UTC www.sun.com [Source type: Reference]

.Once the IP address is received, a TCP connection to the host may be established.^ Once they have that server's IP address, they connect to it.
  • Free DNS Tutorial - Provided by Laynetworks.com 19 January 2010 9:54 UTC laynetworks.com [Source type: FILTERED WITH BAYES]

^ Display the IP address(es) of the host.
  • domainname(1): show/set system's host name - Linux man page 19 January 2010 18:018 UTC linux.die.net [Source type: Reference]

^ When TCP/IP software is installed on a host, the address (not the name!
  • Domain Name System - Hill2dot0 19 January 2010 9:54 UTC www.hill2dot0.com [Source type: Reference]

Background

.In the days of ARPANET, when the internet was in its infancy, a file known as hosts.txt contained a list of hosts and their corresponding IP addresses.^ Display the IP address(es) of the host.
  • domainname(1): show/set system's host name - Linux man page 19 January 2010 18:018 UTC linux.die.net [Source type: Reference]

^ Q. How is an Internet address translated to an IP address?
  • Domain Name System FAQ | MOREnet 19 January 2010 9:54 UTC www.more.net [Source type: Reference]

^ Each domain name corresponds to a numeric IP (Internet Protocol) address.
  • Glossary - Name.com 19 January 2010 9:54 UTC www.name.com [Source type: General]

.Every night, all hosts connected to ARPANET would fetch an updated copy of this file from a central site.^ Upload all files to the new host.
  • domain name registration - how to choose, register or transfer domain names 19 January 2010 9:54 UTC www.isitebuild.com [Source type: General]

^ Every time a change was made, all of the host files had to be updated.

^ Once or twice a week every network connected computer was downloading the new version of HOSTS to keep this information up to date.
  • Triple.com - Articles: DNS (Domain Name System) History 19 January 2010 9:54 UTC www.triple.com [Source type: General]

.As the internet began to grow larger and larger, it became apparent that it was infeasible to continue with this approach.^ The new Internet continued to grow throughout the 70's with the creation of electronic mail (e-mail) and newsgroups.
  • History of the Internet Domain Name Frequently Asked Questions (FAQ) @ DomainAvenue.com | Domain Name Registration and Web Hosting on IBM/Hewlett-Packard (HP) Compaq Servers running Red Hat Linux 7.x w/Apache 19 January 2010 9:54 UTC www.domainavenue.com [Source type: Reference]

^ Since 1981 the number of hosts over the internet began to grow in geometric progression and the flat plain text file became just too big.
  • Triple.com - Articles: DNS (Domain Name System) History 19 January 2010 9:54 UTC www.triple.com [Source type: General]

^ This approach partly reflects the present technical infeasibility of effectively blocking undesirable Internet content without intruding on First Amendment rights.
  • Protecting Domain Name Assets 19 January 2010 9:54 UTC www.nysscpa.org [Source type: Reference]

Top Level Domains

.To begin a search for an IP address, we can choose to narrow our search down according to the type of website we are looking at.^ A typical IP address looks like this: .

^ Domain names are linked to IP addresses by a DNS server; when you type in "www.bt.com/broadband", the DNS computer will find the corresponding IP address so that you can be taken to the site.

^ The domain name system (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses.

.Common domain names include .com (commercial), .edu (educational) and .org (non-profit organisation).^ Some of it's functions include; management of the DNS, allocation of IP addresses and resolving domain name disputes.
  • Domain Name Tutorial, Domain Name Marketing Strategy, Facts, Tutorials, Articles, Web Hosting 19 January 2010 9:54 UTC www.devnic.com [Source type: General]

^ October 1984 RFC 920 establishes 7 generic top level domains (gTLDs, including .com, .net, .org and .gov) to provide domain space for corporations, non-profits, schools, networks, US government offices and the US military.
  • History of the Domain Name System 19 January 2010 9:54 UTC cyber.law.harvard.edu [Source type: FILTERED WITH BAYES]

^ TLDs: Top-level domains, such as .com, .net, and .org.
  • WDVL: The (Domain) Name Game 19 January 2010 9:54 UTC wdvl.internet.com [Source type: General]

.We can also seek a specific server by its country domain.^ Country Specific Domain Names - eg.
  • Domain Names 101 : Small Business Support Network 19 January 2010 9:54 UTC www.ozsmallbiz.net [Source type: General]

^ Poisoning a DNS server occurs when hackers alter the DNS records for a specific domain, redirecting unsuspecting users to a different Web site than the authentic one.
  • DNS - Domain Name System - DNS Lookup and Architecture Basics 19 January 2010 9:54 UTC compnetworking.about.com [Source type: General]

^ DNS servers map domain names to their specific IP address, directing internet inquiries to the appropriate location.
  • Domain Name System (DNS) still at risk | PickyDomains 19 January 2010 9:54 UTC www.pickydomains.com [Source type: News]

.For example, .co.uk belongs to the United Kingdom and .au belongs to Australia.^ Function of the names has been loosened For example, mariners.org Two-letter country codes .us for United States .uk for United Kingdom .de for Germany Domains are case insensitive Fully-qualified names A host's fully-qualified name is its hostname and its domain name, including the "."
  • CptS 302: Domain Name System (DNS) 19 January 2010 9:54 UTC www.eecs.wsu.edu [Source type: Reference]

^ These are commonly used for municipalities such as cities, police stations, and other organization in the US, while abroad they are used as main naming schemes for many domains.  In some countries there are sub-domains indicating the type of organization such as ac.uk, co.uk, sch.uk in the United Kingdom and edu.au and com.au in Australia.

^ The record below is an example of how an A record should look: www.safeDNS.co.uk IN A 81.201.128.1333 .
  • DNS, Domain Name System - SafeDNS FAQs 19 January 2010 18:018 UTC www.safedns.co.uk [Source type: General]

Resouce Records

.These are the records that are handed back to the resolver based on the request it makes.^ It then returns its results to the DNS resolver; assuming it has found a result, the resolver duly caches that result for future use, and hands the result back to the software which initiated the request.
  • Tuna SAKAR (MCP,MCTS,MCSA+S+M,MCSE+S+M,MCITP:EA,CCNA) - Domain Name System 19 January 2010 9:54 UTC tunasakar.com [Source type: Reference]

^ These days, Mockapetris makes his living as chief scientist for Nominum Inc., a Redwood City, Calif.-based provider of IP address infrastructure software.

^ These are a reverse lookup record to aid in making sure your domain names are who they say they are.
  • Domain Name System (DNS) Simplified | Copier Catalog 19 January 2010 9:54 UTC www.copiercatalog.com [Source type: General]

The records are kept in ASCII text, and are presented with the following fields:
Domain Name 
The domain to which the record applies. Multiple domains may exist, and they are all returned together to the resolver
Time to Live
A general indication of how long a record has before it can be considered out of date. Actual dates are not used here, rather, a value (678000 for example) is assigned to indicate how stable the record is. The lower the value, the more likely it would have changed recently.
Type 
What kind of record we are looking at. More information will be provided below
Class
Value
Type Meaning Value
A IP address of host 32 bit integer
MX Mail Exchange The domain that will accept mail
CNAME Canonical Name A fuller version of a domain name
eg The CNAME of www.google.com is google.navigation.opendns.com

Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

English

Proper noun

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  1. (computing) (Internet) The distributed database, sometimes including all the supporting hardware or software infrastructure, the Internet uses to translate hostnames into IP numbers and provide other domain related information.^ Domain Name Service (DNS) is the means by which Internet domain names are translated into IP addresses , or IP addresses are translated into domain names.
    • DNS - Domain Name System 19 January 2010 9:54 UTC www.inetdaemon.com [Source type: Reference]

    ^ The Domain Name System ( DNS ) is a system, which contains domain names; it translates all hostnames into the IP addresses that is necessary for delivering information.
    • ELDEV: Domain Registration 19 January 2010 18:018 UTC www.eldev.com [Source type: Reference]

    ^ This is a special "domain" which is used to do reverse-lookup of IP addresses back into hostnames.
    • Chapter�26.�The Domain Name System 19 January 2010 9:54 UTC www.netbsd.org [Source type: Reference]

    • BIND 9 Administrator Reference Manual (9.3.2), Internet Systems Consortium, Inc., http://www.bind9.net/manual/bind/9.3.2/Bv9ARM.ch01.html
      The purpose of this document is to explain the installation and upkeep of the BIND software package, and we begin by reviewing the fundamentals of the Domain Name System (DNS) as they relate to BIND. ... The Domain Name System (DNS) is the hierarchical, distributed database. It stores information for mapping Internet host names to IP addresses and vice versa, mail routing information, and other data used by Internet applications.

Synonyms

See also


Citable sentences

Up to date as of December 13, 2010

Here are sentences from other pages on Domain Name System, which are similar to those in the above article.








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