Dynamic Host Configuration Protocol: Wikis

  

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.The Dynamic Host Configuration Protocol (DHCP) is a computer networking protocol used by hosts (DHCP clients) to retrieve IP address assignments and other configuration information.^ DHCP delivers automated management of IP addresses and configurations .

^ Dynamic Host configuration Protocol (DHCP) server .
  • Dynamic Host configuration Protocol (DHCP) server - Symbian Developer Community 1 February 2010 7:44 UTC developer.symbian.org [Source type: FILTERED WITH BAYES]

^ IP address - client IP adderess.
  • Tiny DHCP Server :: powerful DHCP service for Windows 19 January 2010 18:39 UTC www.softcab.com [Source type: General]

.DHCP uses a client-server architecture.^ DHCP is based on a client-server relationship, in which the DHCP client, e.g.
  • OIT Support for DHCP 19 January 2010 18:39 UTC www.auburn.edu [Source type: Reference]

^ A DHCP server listens for client requests.
  • Linux Host Configuration with DHCP 1 February 2010 7:44 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ LTSP 4.1 uses dhcpcd as the dhcp client.
  • SourceForge.net: DHCP - ltsp 19 January 2010 18:39 UTC sourceforge.net [Source type: FILTERED WITH BAYES]

.The client sends a broadcast request for configuration information.^ A DHCP server sends the configuration information back to the client.
  • DHCP Overview - JUNOS 9.2 System Basics Configuration Guide 19 January 2010 18:39 UTC www.juniper.net [Source type: FILTERED WITH BAYES]

^ When a client broadcasts a request for a configuration, the client includes its vendor client class.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ The client sends a message to request configuration information.
  • DHCP Overview - JUNOS 9.2 System Basics Configuration Guide 19 January 2010 18:39 UTC www.juniper.net [Source type: FILTERED WITH BAYES]

.The DHCP server receives the request and responds with configuration information from its configuration database.^ Rebuilding the DHCP Database on another server .
  • Intranet Journal: Intranet Management - DHCP 19 January 2010 18:39 UTC www.intranetjournal.com [Source type: FILTERED WITH BAYES]

^ The DHCP server receives a broadcast request from a client.
  • RFC 4390 - Dynamic Host Configuration Protocol (DHCP) over InfiniBand 1 February 2010 7:44 UTC www.rfc-archive.org [Source type: Reference]

^ Displays information about server database configuration for the specified DHCP server.
  • Microsoft Windows XP - Netsh commands for DHCP 19 January 2010 18:39 UTC www.microsoft.com [Source type: Reference]

.In the absence of DHCP, all hosts on a network assign themselves IP addresses, this is known as APIPA. The IP address can also be configured manually, however this should not be practised on a network of ten computers or more because if two computers have the same IP address they will not be able to communicate with one another.^ IP address as well as a local network IP address.
  • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

^ DHCP delivers automated management of IP addresses and configurations .

^ Assign multiple IP addresses to network interfaces.
  • Cisco IOS Release 12.0 Network Protocols Configuration Guide, Part 1 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

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

History

.RFC 1531 initially defined DHCP as a standard-track protocol in October 1993, succeeding the Bootstrap Protocol (BOOTP).^ (DHCP is defined in RFC 1531.
  • Cisco IOS Release 12.0 Network Protocols Configuration Guide, Part 1 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]
  • Cisco IOS IP Configuration Guide, Release 12.2 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

^ RFC 1541 defines DHCP. .

^ RFC 951 - BOOTSTRAP PROTOCOL (BOOTP).
  • Infos about the Internet Protocol (Version 4) and more 1 February 2010 7:44 UTC mark.doll.name [Source type: Reference]

.The next update, RFC 2131 released in 1997 is the current DHCP definition for Internet Protocol version 4 (IPv4) networks.^ Release the current DHCP configuration.
  • Windows - Displaying, Releasing and Renewing a DHCP Lease 19 January 2010 18:39 UTC kb.wisc.edu [Source type: General]

^ The framework for the DHCP protocol is defined in RFC 2131.
  • Understanding DHCP 19 January 2010 18:39 UTC www.tech-faq.com [Source type: FILTERED WITH BAYES]

^ DHCP is RFC 2131 .

.The extensions of DHCP for IPv6 (DHCPv6) were published as RFC 3315.^ DHCPv6 DHCP for IPv6 is defined in [ RFC3315 ].
  • draft-winterbottom-geopriv-held-dhcp-discovery-00 - HELD Service Discovery using DHCP 19 January 2010 18:39 UTC tools.ietf.org [Source type: Reference]

^ RFC 3203 ] DHCP reconfigure extension.
  • Protocol: DHCP ( Dynamic Host Configuration Protocol ) 19 January 2010 18:39 UTC www.protocolbase.net [Source type: Reference]

^ The DHCP is a successor to an older protocol that is known as BOOTP.The specifications for the DHCP are published in RFC 2131 .
  • DHCP 19 January 2010 18:39 UTC it.toolbox.com [Source type: FILTERED WITH BAYES]

Technical overview

.Dynamic Host Configuration Protocol automates network-parameter assignment to network devices from one or more fault-tolerant DHCP servers.^ Dynamic Host configuration Protocol (DHCP) server .
  • Dynamic Host configuration Protocol (DHCP) server - Symbian Developer Community 1 February 2010 7:44 UTC developer.symbian.org [Source type: FILTERED WITH BAYES]

^ IP number over the network from a DHCP server.
  • DHCP FAQ 19 January 2010 18:39 UTC www.wsu.edu [Source type: General]

^ BOOTP packets carry Dynamic Host Configuration Protocol (DHCP) information.
  • Cisco IOS Release 12.0 Network Protocols Configuration Guide, Part 1 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

.Even in small networks, DHCP is useful because it can make it easy to add new machines to the network.^ Used to manage the DHCP network tables.
  • DHCP Command-Line Utilities (System Administration Guide: IP Services) - Sun Microsystems 19 January 2010 18:39 UTC docs.sun.com [Source type: Reference]

^ What DHCP clients are in use on the network?
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ How to Add a DHCP Network ( dhcpconfig ) .
  • Starting and Stopping the DHCP Service - System Administration Guide: IP Services 19 January 2010 18:39 UTC dlc.sun.com [Source type: Reference]
  • Modifying DHCP Service Options (Task Map) - System Administration Guide: IP Services 19 January 2010 18:39 UTC dlc.sun.com [Source type: Reference]

.When a DHCP-configured client (a computer or any other network-aware device) connects to a network, the DHCP client sends a broadcast query requesting necessary information from a DHCP server.^ DHCP client: Configuring a DHCP is very easy.
  • NewOrder - news: Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC neworder.box.sk [Source type: General]

^ The DHCP server checks relay information.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ SHARED connects the client to a shared server.
  • Configuration Parameters 1 February 2010 7:44 UTC www.mscd.edu [Source type: Reference]

.The DHCP server manages a pool of IP addresses and information about client configuration parameters such as default gateway, domain name, the DNS servers, other servers such as time servers, and so forth.^ DHCP client: Configuring a DHCP is very easy.
  • NewOrder - news: Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC neworder.box.sk [Source type: General]

^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ An exchange takes place during which the DHCP server assigns an IP address to the client and tells the client certain key network configuration parameters (such as name server addresses for example).
  • NetBSD DHCP HOWTO 19 January 2010 18:39 UTC www.netbsd.org [Source type: General]

.On receiving a valid request, the server assigns the computer an IP address, a lease (length of time the allocation is valid), and other IP configuration parameters, such as the subnet mask and the default gateway.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ In the example above, default-lease-time is an example of a parameter.

^ The IP address lease time will be 10 minutes.
  • ImageStream Internet Solutions, Inc. - DHCP Server Configuration 19 January 2010 18:39 UTC support.imagestream.com [Source type: Reference]

.The query is typically initiated immediately after booting, and must complete before the client can initiate IP-based communication with other hosts.^ The host cannot communicate with other hosts on the network.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ The whole process takes place immediately after the new computer boots, and to be successful, it has to be completed before initiating IP based communication with other hosts in the network.
  • DHCP (Dynamic Host Configuration Protocol) 1 February 2010 7:44 UTC www.ntchosting.com [Source type: FILTERED WITH BAYES]

^ Typically, the address denotes the client's IP address.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

Depending on implementation, the DHCP server may have three methods of allocating IP-addresses:
.
  • dynamic allocation: A network administrator assigns a range of IP addresses to DHCP, and each client computer on the LAN has its IP software configured to request an IP address from the DHCP server during network initialization.^ DHCP client: Configuring a DHCP is very easy.
    • NewOrder - news: Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC neworder.box.sk [Source type: General]

    ^ A. Delete the existing IP address leases from the DHCP server.
    • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

    ^ IP address as well as a local network IP address.
    • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

    .The request-and-grant process uses a lease concept with a controllable time period, allowing the DHCP server to reclaim (and then reallocate) IP addresses that are not renewed (dynamic re-use of IP addresses).
  • automatic allocation: The DHCP server permanently assigns a free IP address to a requesting client from the range defined by the administrator.^ The right to use this IP address is given to the client for a finite period of time, called a lease.
    • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

    ^ A. Delete the existing IP address leases from the DHCP server.
    • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

    ^ A Web request is made the client connects to the DNS/DHCP server.
    • Configuring DHCP and DNS for ISA automatic discovery 19 January 2010 18:39 UTC isaserver.org [Source type: General]

    .This is like dynamic allocation, but the DHCP server keeps a table of past IP address assignments, so that it can preferentially assign to a client the same IP address that the client previously had.
  • static allocation: The DHCP server allocates an IP address based on a table with MAC address/IP address pairs, which are manually filled in (perhaps by a network administrator).^ A. Delete the existing IP address leases from the DHCP server.
    • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

    ^ IP address as well as a local network IP address.
    • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

    ^ As long as the laptop is connected to the network the lease will not expire and the laptop will keep the assigned IP address.

    .Only requesting clients with a MAC address listed in this table will be allocated an IP address.^ IP address - client IP adderess.
    • Tiny DHCP Server :: powerful DHCP service for Windows 19 January 2010 18:39 UTC www.softcab.com [Source type: General]

    ^ Client IP address 32 bits.
    • Protocol: DHCP ( Dynamic Host Configuration Protocol ) 19 January 2010 18:39 UTC www.protocolbase.net [Source type: Reference]

    ^ MAC address of the client.
    • Understanding DHCP 19 January 2010 18:39 UTC www.tech-faq.com [Source type: FILTERED WITH BAYES]

    This feature (which is not supported by all devices) is variously called Static DHCP Assignment (by DD-WRT), fixed-address (by the dhcpd documentation), DHCP reservation or Static DHCP (by Cisco/Linksys), and IP reservation or MAC/IP binding (by various other router manufacturers).

Technical details

.DHCP uses the same two ports assigned by IANA for BOOTP: 67/udp for sending data to the server, and 68/udp for data to the client.^ A DHCP server sends the configuration information back to the client.
  • DHCP Overview - JUNOS 9.2 System Basics Configuration Guide 19 January 2010 18:39 UTC www.juniper.net [Source type: FILTERED WITH BAYES]

^ The messages from the client to the server use UDP source port 68 and UDP destination port 67.
  • What Is DHCP? - Understanding Dynamic Host Configuration Protocol - Softpedia 1 February 2010 7:44 UTC news.softpedia.com [Source type: General]

^ Only if the DHCP client were specifically written to make use of the answer from a BOOTP server.

.DHCP operations fall into four basic phases: IP discovery, IP lease offer, IP request, and IP lease acknowledgement.^ DHCP request state operations.
  • gPXE: net/udp/dhcp.c File Reference 19 January 2010 18:39 UTC www.etherboot.org [Source type: Reference]

^ This is the message used to request an IP address lease from a DHCP server.
  • Understanding DHCP 19 January 2010 18:39 UTC www.tech-faq.com [Source type: FILTERED WITH BAYES]

^ Figure 2 shows the messages exchanged during the four basic DHCP operational phases.
  • DHCP and Windows NT 19 January 2010 18:39 UTC www.garykessler.net [Source type: FILTERED WITH BAYES]

.Where a DHCP client and server are on the same subnet, they will communicate via UDP broadcasts.^ The DHCP server receives a broadcast request from a client.
  • RFC 4390 - Dynamic Host Configuration Protocol (DHCP) over InfiniBand 1 February 2010 7:44 UTC www.rfc-archive.org [Source type: Reference]

^ A DHCP server listens for client requests.
  • Linux Host Configuration with DHCP 1 February 2010 7:44 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ DHCP server listens on UDP 67 port, DHCP client - on UDP 68 port.
  • MikroTik RouterOS V2.7 DHCP Client and Server 19 January 2010 18:39 UTC www.mikrotik.com [Source type: Reference]

.When the client and server are on different subnets, IP discovery and IP request messages are sent via UDP broadcasts, but IP lease offer and IP lease acknowledgement messages are sent via unicast.^ The DHCP Acknowledge message is actually the process of assigning the IP address lease to the client.
  • Understanding DHCP 19 January 2010 18:39 UTC www.tech-faq.com [Source type: FILTERED WITH BAYES]

^ DHCP offers: When a DHCP server receives an IP lease request from a client, it extends an IP lease offer.

^ DHCPNak (sent from server to client) .
  • Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC ucomm.wayne.edu [Source type: Reference]

DHCP discovery

.The client broadcasts messages on the physical subnet to discover available DHCP servers.^ Since the message is broadcast, all DHCP servers can receive it.
  • DHCP (Dynamic Host Configuration Protocol) (Linktionary term) 19 January 2010 18:39 UTC www.linktionary.com [Source type: General]

^ Boot the client and watch the DHCP message exchange between the client and server(s).
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ The DHCP server receives a broadcast request from a client.
  • RFC 4390 - Dynamic Host Configuration Protocol (DHCP) over InfiniBand 1 February 2010 7:44 UTC www.rfc-archive.org [Source type: Reference]

.Network administrators can configure a local router to forward DHCP packets to a DHCP server from a different subnet.^ DNS Administrator, if DHCP server is not configured for dynamic DNS updates .
  • Modifying DHCP Service Options (Task Map) - System Administration Guide: IP Services 19 January 2010 18:39 UTC dlc.sun.com [Source type: Reference]

^ IP number over the network from a DHCP server.
  • DHCP FAQ 19 January 2010 18:39 UTC www.wsu.edu [Source type: General]

^ DHCP Manager helps network administrators configure and monitor DHCP servers.
  • Dynamic Host Configuration Protocol for Windows 2000 1 February 2010 7:44 UTC technet.microsoft.com [Source type: Reference]

.This client-implementation creates a User Datagram Protocol (UDP) packet with the broadcast destination of 255.255.255.255 or the specific subnet broadcast address.^ The Source address is 0.0.0.0 and the Destination is the broadcast address 255.255.255.255.
  • DHCP (Dynamic Host Configuration Protocol) Basics 19 January 2010 18:39 UTC support.microsoft.com [Source type: Reference]

^ Enable forwarding and specify the destination address for forwarding UDP broadcast packets, including BOOTP. .
  • Cisco IOS Release 12.0 Network Protocols Configuration Guide, Part 1 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

^ This is a broadcast using 255.255.255.255 as the destination address and 0.0.0.0 as the source address.

.A DHCP client can also request its last-known IP address (in the example below, 192.168.1.100).^ DHCP 'client identifier' option of the request .
  • http://www.mikrotik.com/testdocs/ros/2.9/ip/dhcp_content.php 19 January 2010 18:39 UTC www.mikrotik.com [Source type: FILTERED WITH BAYES]

^ The DHCP protocol gives and allocates IP addresses to IP clients.
  • MikroTik RouterOS V2.7 DHCP Client and Server 19 January 2010 18:39 UTC www.mikrotik.com [Source type: Reference]
  • http://www.mikrotik.com/testdocs/ros/2.9/ip/dhcp_content.php 19 January 2010 18:39 UTC www.mikrotik.com [Source type: FILTERED WITH BAYES]

^ The DHCP client then sends a request message to the DHCP SERVER (DHCP REQUEST) accepting the IP address.
  • NewOrder - news: Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC neworder.box.sk [Source type: General]

.If the client remains connected to a network for which this IP is valid, the server might grant the request.^ A Web request is made the client connects to the DNS/DHCP server.
  • Configuring DHCP and DNS for ISA automatic discovery 19 January 2010 18:39 UTC isaserver.org [Source type: General]

^ SHARED connects the client to a shared server.
  • Configuration Parameters 1 February 2010 7:44 UTC www.mscd.edu [Source type: Reference]

^ IP number over the network from a DHCP server.
  • DHCP FAQ 19 January 2010 18:39 UTC www.wsu.edu [Source type: General]

.Otherwise, it depends whether the server is set up as authoritative or not.^ Setting up a DHCP Server .

^ I have a 2003 server set up as DC, DNS and DHCP .
  • How to test DHCP from a distance 19 January 2010 18:39 UTC www.windowsbbs.com [Source type: General]

^ I set up a DHCP server on ubuntu using GADMIN TOOLS DHCPD which is serving a wireless network.
  • Why Does DHCP Server on Ubuntu Not Work? | LinkedIn Answers | LinkedIn 19 January 2010 18:39 UTC www.linkedin.com [Source type: FILTERED WITH BAYES]

.An authoritative server will deny the request, making the client ask for a new IP immediately.^ If it has not, the server checks to see if the client has requested a new lease.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ A DHCP server listens for client requests.
  • Linux Host Configuration with DHCP 1 February 2010 7:44 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ Opcode for a request from client to server.
  • gPXE: include/gpxe/dhcp.h File Reference 19 January 2010 18:39 UTC www.etherboot.org [Source type: Reference]

.A non-authoritative server simply ignores the request, leading to an implementation-dependent timeout for the client to give up on the request and ask for a new IP address.^ Non DHCP Clients : Clients that do not support DHCP have to be manually assigned with IP addresses.
  • Understanding DHCP 19 January 2010 18:39 UTC www.tech-faq.com [Source type: FILTERED WITH BAYES]

^ After a server offers an IP address to a client, the offer is cached.
  • Modifying DHCP Service Options (Task Map) - System Administration Guide: IP Services 19 January 2010 18:39 UTC dlc.sun.com [Source type: Reference]

^ By default, the server pings an IP address before offering the address to a client.
  • Modifying DHCP Service Options (Task Map) - System Administration Guide: IP Services 19 January 2010 18:39 UTC dlc.sun.com [Source type: Reference]

DHCP offer

.When a DHCP server receives an IP lease request from a client, it reserves an IP address for the client and extends an IP lease offer by sending a DHCPOFFER message to the client.^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ DHCP servers can interoperate with BOOTP clients.
  • DHCP, Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.networksorcery.com [Source type: Reference]

^ Since the message is broadcast, all DHCP servers can receive it.
  • DHCP (Dynamic Host Configuration Protocol) (Linktionary term) 19 January 2010 18:39 UTC www.linktionary.com [Source type: General]

.This message contains the client's MAC address, the IP address that the server is offering, the subnet mask, the lease duration, and the IP address of the DHCP server making the offer.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ Comments: The client may offer a suggested IP address in its DHCPDISCOVER message.
  • DHCP: the Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC gicl.cs.drexel.edu [Source type: FILTERED WITH BAYES]

.The server determines the configuration based on the client's hardware address as specified in the CHADDR (Client Hardware Address) field.^ The DHCP server can configure a client with any of the options specified in RFC 2132.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ Chaddr chaddr 16 Client hardware address.
  • Net::DHCP::Packet - search.cpan.org 19 January 2010 18:39 UTC search.cpan.org [Source type: Reference]
  • Net::DHCP::Packet 19 January 2010 18:39 UTC cpan.uwinnipeg.ca [Source type: Reference]

^ Construct DHCP client hardware address field and broadcast flag.
  • gPXE: net/udp/dhcp.c File Reference 19 January 2010 18:39 UTC www.etherboot.org [Source type: Reference]
  • gPXE: include/gpxe/dhcp.h File Reference 19 January 2010 18:39 UTC www.etherboot.org [Source type: Reference]

.Here the server, 192.168.1.1, specifies the IP address in the YIADDR (Your IP Address) field.^ Your IP address .
  • Protocol: DHCP ( Dynamic Host Configuration Protocol ) 19 January 2010 18:39 UTC www.protocolbase.net [Source type: Reference]

^ Specifies a list of IP addresses for NetBIOS name servers (NBNS).¹ .
  • Dynamic Host Configuration Protocol for Windows 2000 1 February 2010 7:44 UTC technet.microsoft.com [Source type: Reference]

^ Change the ip address of the WRT to 192.168.1.2.
  • IP address? DHCP? - Wireless Routers - Linksys Community Forums 19 January 2010 18:39 UTC forums.linksysbycisco.com [Source type: FILTERED WITH BAYES]

DHCP request

.A client can receive DHCP offers from multiple servers, but it will accept only one DHCP offer and broadcast a DHCP request message.^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ DHCP offers: When a DHCP server receives an IP lease request from a client, it extends an IP lease offer.

^ Since the message is broadcast, all DHCP servers can receive it.
  • DHCP (Dynamic Host Configuration Protocol) (Linktionary term) 19 January 2010 18:39 UTC www.linktionary.com [Source type: General]

.Based on the Transaction ID field in the request, servers are informed whose offer the client has accepted.^ Transaction - A single request for an object from a client to server.
  • DHCP Server Testing :: Test Plans :: Ixia - Leader in Converged IP Testing 19 January 2010 18:39 UTC www.ixiacom.com [Source type: Reference]

^ The client ignores the transaction-id field in the received Reconfigure message.
  • RFC 3315 (rfc3315) - Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

^ A DHCP server listens for client requests.
  • Linux Host Configuration with DHCP 1 February 2010 7:44 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

.When other DHCP servers receive this message, they withdraw any offers that they might have made to the client and return the offered address to the pool of available addresses.^ A Web request is made the client connects to the DNS/DHCP server.
  • Configuring DHCP and DNS for ISA automatic discovery 19 January 2010 18:39 UTC isaserver.org [Source type: General]

^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ Since the message is broadcast, all DHCP servers can receive it.
  • DHCP (Dynamic Host Configuration Protocol) (Linktionary term) 19 January 2010 18:39 UTC www.linktionary.com [Source type: General]

DHCP acknowledgement

.When the DHCP server receives the DHCPREQUEST message from the client, the configuration processes enters its final phase.^ DHCP client: Configuring a DHCP is very easy.
  • NewOrder - news: Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC neworder.box.sk [Source type: General]

^ A DHCP server sends the configuration information back to the client.
  • DHCP Overview - JUNOS 9.2 System Basics Configuration Guide 19 January 2010 18:39 UTC www.juniper.net [Source type: FILTERED WITH BAYES]

^ DHCP servers can interoperate with BOOTP clients.
  • DHCP, Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.networksorcery.com [Source type: Reference]

.The acknowledgement phase involves sending a DHCPACK packet to the client.^ The server sends a DHCPACK unicast to the client.
  • CCNP 1: Advanced IP Addressing Management > DHCP and Easy IP 19 January 2010 18:39 UTC www.ciscopress.com [Source type: FILTERED WITH BAYES]

^ After the client accepts the offered parameters, the server sends an ``ack'' (acknowledgment) message completing the process.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ The client finds a problem with the assigned address of DhcpAck, it sends DhcpDecline to the server, and restarts from step 1.
  • DHCP 19 January 2010 18:39 UTC jhmcis.jhmi.edu [Source type: FILTERED WITH BAYES]

.This packet includes the lease duration and any other configuration information that the client might have requested.^ This configuration information includes: .
  • Intranet Journal: Intranet Management - DHCP 19 January 2010 18:39 UTC www.intranetjournal.com [Source type: Reference]

^ When a client broadcasts a request for a configuration, the client includes its vendor client class.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ Clients can request an extension of the address lease.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

.At this point, the IP configuration process is completed.^ At this point the process is complete, and the client will configure its IP information accordingly.
  • Dynamic Host Configuration Protocol (DHCP) Definition : Learn-Networking.com 1 February 2010 7:44 UTC learn-networking.com [Source type: General]
  • An Introduction to Dynamic Host Configuration Protocol : Learn-Networking.com 1 February 2010 7:44 UTC learn-networking.com [Source type: General]

^ To complete the fault tolerance plan, the routers connecting the remote sites to Corp HQ need DHCP relay agents configured to point to the DHCP servers.
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Whereas DHCP unicast scopes provide client configurations by allocating ranges of IP addresses for point-to-point communication between two networked computers, multicast scopes provide ranges for multicast IP addresses.
  • How DHCP Technology Works: Dynamic Host Configuration Protocol (DHCP) 19 January 2010 18:39 UTC technet.microsoft.com [Source type: Reference]

.The protocol expects the DHCP client to configure its network interface with the negotiated parameters.^ DHCP client: Configuring a DHCP is very easy.
  • NewOrder - news: Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC neworder.box.sk [Source type: General]

^ An Internet host that returns configuration parameters to DHCP clients.
  • DHCP, Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.networksorcery.com [Source type: Reference]

^ The client is configured and has access to the network.
  • DHCP Overview - JUNOS 9.2 System Basics Configuration Guide 19 January 2010 18:39 UTC www.juniper.net [Source type: FILTERED WITH BAYES]

DHCPDISCOVER
UDP Src=0.0.0.0 sPort=68
Dest=255.255.255.255 dPort=67
OP HTYPE HLEN HOPS
0x01 0x01 0x06 0x00
XID
0x3903F326
SECS FLAGS
0x0000 0x0000
CIADDR
0x00000000
YIADDR
0x00000000
SIADDR
0x00000000
GIADDR
0x00000000
CHADDR
0x00053C04
0x8D590000
0x00000000
0x00000000
192 octets of 0's. BOOTP legacy
Magic Cookie
0x63825363
DHCP Options
DHCP option 53: DHCP Discover
DHCP option 50: 192.168.1.100 requested
DHCP option 55: Parameter Request List:
Request Subnet Mask (1), Router (3), Domain Name (15),
Domain Name Server (6)
DHCPOFFER
UDP Src=192.168.1.1 sPort=67
Dest=255.255.255.255 dPort=68
OP HTYPE HLEN HOPS
0x02 0x01 0x06 0x00
XID
0x3903F326
SECS FLAGS
0x0000 0x0000
CIADDR
0x00000000
YIADDR
0xC0A80164
SIADDR
0xC0A80101
GIADDR
0x00000000
CHADDR
0x00053C04
0x8D590000
0x00000000
0x00000000
192 octets of 0's. BOOTP legacy
Magic Cookie
0x63825363
DHCP Options
DHCP option 53: DHCP Offer
DHCP option 1: 255.255.255.0 subnet mask
DHCP option 3: 192.168.1.1 router
DHCP option 51: IP lease time in seconds, 1 day = 86400 s
DHCP option 54: 192.168.1.1 DHCP server
DHCP option 6: DNS servers 9.7.10.15, 9.7.10.16, 9.7.10.18
DHCPREQUEST
UDP Src=0.0.0.0 sPort=68
Dest=255.255.255.255 dPort=67
OP HTYPE HLEN HOPS
0x01 0x01 0x06 0x00
XID
0x3903F326
SECS FLAGS
0x0000 0x0000
CIADDR
0x00000000
YIADDR
0xC0A80164
SIADDR
0xC0A80101
GIADDR
0x00000000
CHADDR
0x00053C04
0x8D590000
0x00000000
0x00000000
192 octets of 0's. BOOTP legacy
Magic Cookie
0x63825363
DHCP Options
DHCP option 53: DHCP Request
DHCP option 50: 192.168.1.100 requested
.DHCP option 54: 192.168.1.1 DHCP server.^ The version of the DHCP Server 192.168.0.100 is 5.6.
  • Microsoft Windows XP - Netsh commands for DHCP 19 January 2010 18:39 UTC www.microsoft.com [Source type: Reference]

^ DHCP options from /ip dhcp-server option list.
  • http://www.mikrotik.com/testdocs/ros/2.9/ip/dhcp_content.php 19 January 2010 18:39 UTC www.mikrotik.com [Source type: FILTERED WITH BAYES]

^ Defines BOOTP/DHCP options 85 (NDS Servers), 86 (NDS Tree Name) and 87 (NDS Context).
  • Protocol: DHCP ( Dynamic Host Configuration Protocol ) 19 January 2010 18:39 UTC www.protocolbase.net [Source type: Reference]

DHCPACK
UDP Src=192.168.1.1 sPort=67
Dest=255.255.255.255 dPort=68
OP HTYPE HLEN HOPS
0x02 0x01 0x06 0x00
XID
0x3903F326
SECS FLAGS
0x0000 0x0000
CIADDR (Client IP Address)
0x00000000
YIADDR (Your IP Address)
0xC0A80164
SIADDR (Server IP Address)
0xC0A80101
GIADDR (Gateway IP Address switched by relay)
0x00000000
CHADDR (Client Hardware Address)
0x00053C04
0x8D590000
0x00000000
0x00000000
192 octets of 0's. BOOTP legacy
Magic Cookie
0x63825363
DHCP Options
DHCP option 53: DHCP ACK
DHCP option 1: 255.255.255.0 subnet mask
DHCP option 3: 192.168.1.1 router
DHCP option 51: 1 day IP lease time
DHCP option 54: 192.168.1.1 DHCP server
DHCP option 6: DNS servers 9.7.10.15, 9.7.10.16, 9.7.10.18
.After the client obtains an IP address, the client may use the Address Resolution Protocol (ARP) to prevent IP conflicts caused by overlapping address pools of DHCP servers.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ B. Address conflicts between client computers and servers are prevented.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

DHCP information

.A DHCP client may request more information than the server sent with the original DHCPOFFER. The client may also request repeat data for a particular application.^ The DHCP server checks relay information.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ DHCP server (or server) A node that responds to requests from clients, and may or may not be on the same link as the client(s).
  • RFC 3315 (rfc3315) - Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]
  • RFC3315 - Dynamic Host Configuration Protocol for IPv6 (DHCP_�й�Э�������� 1 February 2010 7:44 UTC www.cnpaf.net [Source type: Reference]

^ This information may be used by the DHCP server to better serve clients based on whether their request was originally broadcast or unicast.
  • DHCP related RFCs (DNS, BIND Nameserver, DHCP, LDAP and Directory Services) 1 February 2010 7:44 UTC www.bind9.net [Source type: Reference]

.For example, browsers use DHCP Inform to obtain web proxy settings via WPAD.^ For example, the network administrator might have updated settings on the DHCP server since the lease was acquired or last renewed.
  • Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC ucomm.wayne.edu [Source type: Reference]

^ The entire DHCP message (setting the MAC field of the authentication option to zero), including the DHCP message header and the options field, is used as input to the HMAC- MD5 computation function.
  • RFC 3315 (rfc3315) - Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

^ Specify that the router use the DHCP client-proxy.
  • Cisco IOS Release 12.0 Dial Solutions Configuration Guide - Configuring Protocol Translation & Virtual Asynchronous Devices - Cisco Systems 1 February 2010 7:44 UTC cco.cisco.com [Source type: Reference]

.Such queries do not cause the DHCP server to refresh the IP expiry time in its database.^ The DHCP server database is organized as a tree.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ While the DHCP server protocol is designed to support dynamic management of IP addresses, there is nothing to stop someone from implementing a server that uses the DHCP protocol, but does not provide that kind of support.

DHCP releasing

.The client sends a request to the DHCP server to release the DHCP information and the client deactivates its IP address.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ The DHCP server checks relay information.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

.As client devices usually do not know when users may unplug them from the network, the protocol does not mandate the sending of DHCP Release.^ What protocol and port does DHCP use?

^ There may also be network devices that support DHCP, such as network printers.
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Pooled addresses may then be dynamically assigned to DHCP clients on the network.
  • Dynamic Host Configuration Protocol for Windows 2000 1 February 2010 7:44 UTC technet.microsoft.com [Source type: Reference]

Client configuration parameters

.A DHCP server can provide optional configuration parameters to the client.^ An address configuration parameter that a DHCP server assigns to clients.
  • Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC ucomm.wayne.edu [Source type: Reference]

^ Any host providing configuration parameters.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ The DHCP server can configure a client with any of the options specified in RFC 2132.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

.RFC 2132 describes the available DHCP options defined by Internet Assigned Numbers Authority (IANA) - DHCP and BOOTP PARAMETERS.^ The DHCP server can configure a client with any of the options specified in RFC 2132.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ (DHCP is defined in RFC 1531.
  • Cisco IOS Release 12.0 Network Protocols Configuration Guide, Part 1 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]
  • Cisco IOS IP Configuration Guide, Release 12.2 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

^ These options are defined in RFC 1533.
  • Dynamic Host Configuration Protocol for Windows 2000 1 February 2010 7:44 UTC technet.microsoft.com [Source type: Reference]

.A DHCP client can select, manipulate and overwrite parameters provided by a DHCP server.^ An address configuration parameter that a DHCP server assigns to clients.
  • Dynamic Host Configuration Protocol (DHCP) 1 February 2010 7:44 UTC ucomm.wayne.edu [Source type: Reference]

^ Table 1: Description of fields in a DHCP message Server Client Server (not selected) (selected) v v v .
  • RFC 1541 (rfc1541) - Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

^ The selected DHCP server allocates the address and sends the acknowledgement to the client.
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

[1]

Options

.An option exists to identify the vendor and functionality of a DHCP client.^ Which DHCP options do the DHCP clients support?
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Which DHCP options do DHCP clients in this scope require?
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ Configuring DHCP client option sets .
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

.The information is a variable-length string of characters or octets which has a meaning specified by the vendor of the DHCP client.^ Specifies the client's domain name string.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ Specifies an NVT ASCII character string.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ To define a new option, you need to specify the following information for it: the option's name a description of the option the option's type (for example, IP address, string, integer, and so on) the minimum and maximum allowed values for the option (if the option is an integer) the minimum and maximum allowed length for the option (if the option is an IP address, string, binary or array) For vendor classes, you can define new DHCP options with codes in the range 1 through 254.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

.One method that a DHCP client can utilize to communicate to the server that it is using a certain type of hardware or firmware is to set a value in its DHCP requests called the Vendor Class Identifier (VCI) (Option 60).^ If you configure the same option in more than one set of options, the precedence of the option type decides which the DHCP server offers to the client.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ The documentation supplied by the hardware manufacturer should detail the vendor class identifier as well as the DHCP option codes, data types, and values of any vendor-specific options that the clients will require.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ Microsoft DHCP clients require client identifiers instead of hardware addresses.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

.This method allows a DHCP server to differentiate between the two kinds of client machines and process the requests from the two types of modems appropriately.^ Boot the client and watch the DHCP message exchange between the client and server(s).
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ The DHCP server machine is not working.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ In the 80/20 method, two DHCP servers are configured.
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.Some types of set-top boxes also set the VCI (Option 60) to inform the DHCP server about the hardware type and functionality of the device.^ Fields and options used by DHCP servers.
  • RFC 1541 (rfc1541) - Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

^ The DHCP message type that was received by the DHCP server.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ Some DHCP options have default values.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

.The value that this option is set to give the DHCP server a hint about any required extra information that this client needs in a DHCP response.^ The DHCP server checks relay information.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ Sets a DHCP server option value that will be applied for all scopes defined at the specified DHCP server.
  • Microsoft Windows XP - Netsh commands for DHCP 19 January 2010 18:39 UTC www.microsoft.com [Source type: Reference]

^ Construct a byte-valued DHCP option .
  • gPXE: include/gpxe/dhcp.h File Reference 19 January 2010 18:39 UTC www.etherboot.org [Source type: Reference]

DHCP Relaying

.In small networks DHCP typically uses broadcasts.^ What DHCP clients are in use on the network?
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

^ If a host has knowledge of a previous network address and is unable to contact a local DHCP server, the host may continue to use the previous network address until the lease for that address expires.
  • RFC 1541 (rfc1541) - Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

^ In practice it doesn't matter very much which you use but you must make sure that every host on the network is configured with the same broadcast address.
  • Linux Networking-HOWTO (Previously the Net-3 Howto): Generic Network Configuration Information. 1 February 2010 7:44 UTC mirrors.usc.edu [Source type: FILTERED WITH BAYES]

.However, in some circumstances, unicast addresses will be used, for example: when networks have a single DHCP server that provides IP addresses for multiple subnets.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ IP address as well as a local network IP address.
  • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

^ Assign multiple IP addresses to network interfaces.
  • Cisco IOS Release 12.0 Network Protocols Configuration Guide, Part 1 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

.When a router for such a subnet receives a DHCP broadcast, it converts it to unicast (with a destination MAC/IP address of the configured DHCP server, source MAC/IP of the router itself).^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ DHCP should not require a server on each subnet.
  • RFC 1541 (rfc1541) - Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

^ The IP address of the host as recorded on the DHCP server.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

.The GIADDR field of this modified request is populated with the IP address of the router interface on which it received the original DHCP request.^ Specifies the IP address of the default router for a DHCP client.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ Router> show ip dhcp binding [ address ] .
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ Router# show ip masks address .
  • Cisco IOS IP Configuration Guide, Release 12.2 - Configuring IP Addressing - Cisco Systems 1 February 2010 7:44 UTC cio.cisco.com [Source type: Reference]

.The DHCP server uses the GIADDR field to identify the subnet of the originating device in order to select an IP address from the correct pool.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ To add a subnet definition using the DHCP Server Manager : Select View Subnets.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

^ To modify a subnet definition using the DHCP Server Manager : Select View Subnets.
  • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

.The DHCP server then sends the DHCP OFFER back to the router via unicast.^ Can a DHCP server back up another DHCP server?

^ The server sends back its reply to the relay agent (unicast).
  • DHCP 19 January 2010 18:39 UTC jhmcis.jhmi.edu [Source type: FILTERED WITH BAYES]

^ Here are the features a DHCP server can offer.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

.The router then converts the DHCP OFFER back to a broadcast, sent out on the interface of the original device.^ The "hour or so" would be when the Actiontec's original DHCP lease expires and your router attempts to renew the lease, but does not send the STB specific information.
  • FIOS TV Central website access with Non AT Router? - dslreports.com 19 January 2010 18:39 UTC www.broadbandreports.com [Source type: General]

^ Secondly, a feature of some routers known as "BOOTP forwarding" to forward DHCP or BOOTP requests to a server on another subnet and to forward the replies back to the client.

^ When fully booted, open TCP/IP, switch the interface back to ethernet, select DHCP in the "configure" popup.
  • iMacInTouch: DHCP Issues 19 January 2010 18:39 UTC www.macintouch.com [Source type: FILTERED WITH BAYES]

Security

The basic DHCP protocol became a standard before network security became a significant issue: it includes no security features, and is potentially vulnerable to two types of attacks:[2]
.
  • Unauthorized DHCP Servers: as you cannot specify the server you want, an unauthorized server can respond to client requests, sending client network configuration values that are beneficial to the attacker.^ Deletes a class from the specified DHCP server.
    • Microsoft Windows XP - Netsh commands for DHCP 19 January 2010 18:39 UTC www.microsoft.com [Source type: Reference]

    ^ Specifies the DHCP server to delete.
    • Microsoft Windows XP - Netsh commands for DHCP 19 January 2010 18:39 UTC www.microsoft.com [Source type: Reference]

    ^ You want to configure Srv1 to connect to all the NetWare servers.
    • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

    .As an example, a hacker can hijack the DHCP process to configure clients to use a malicious DNS server or router (see also DNS cache poisoning).
  • Unauthorized DHCP Clients: By masquerading as a legitimate client, an unauthorized client can gain access to network configuration and an IP address on a network it should otherwise not be allowed to use.^ A. Delete the existing IP address leases from the DHCP server.
    • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

    ^ IP address as well as a local network IP address.
    • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

    ^ After the client accepts the address, the DHCP server notifies AAS that the address has been leased.
    • Configuring a Dynamic Host Configuration Protocol (DHCP) server 1 February 2010 7:44 UTC uw714doc.sco.com [Source type: Reference]

    Also, by flooding the DHCP server with requests for IP addresses, it is possible for an attacker to exhaust the pool of available IP addresses, disrupting normal network activity (a denial of service attack).
.To combat these threats RFC 3118 ("Authentication for DHCP Messages") introduced authentication information into DHCP messages, allowing clients and servers to reject information from invalid sources.^ The DHCP server checks relay information.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ Boot the client and watch the DHCP message exchange between the client and server(s).
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ The threat specific to a DHCP server is an invalid client masquerading as a valid client.
  • RFC 3315 (rfc3315) - Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

.Although support for this protocol is widespread, a large number of clients and servers still do not fully support authentication, thus forcing servers to support clients that do not support this feature.^ Thus it is left to the server implementation to support such a feature.

^ What servers support secondary subnet numbers?

^ Specification of the DHCP client-server protocol .
  • RFC 1541 (rfc1541) - Dynamic Host Configuration Protocol 1 February 2010 7:44 UTC www.faqs.org [Source type: Reference]

.As a result, other security measures are usually implemented around the DHCP server (such as IPsec) to ensure that only authenticated clients and servers are granted access to the network.^ Implementation What features or restrictions can DHCP servers have?
  • DHCP 19 January 2010 18:39 UTC jhmcis.jhmi.edu [Source type: FILTERED WITH BAYES]

^ Can a DHCP client boot from a BOOTP server?

^ So clients on one network cannot broadcast DHCP or BOOTP requests to servers on other networks.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

.Addresses should be dynamically linked to a secure DNS server, to allow troubleshooting by name rather than by a potentially unknown address.^ The DNS server is configured to allow dynamic updates.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ C. Disable dynamic updates on the DNS server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ While the DHCP server protocol is designed to support dynamic management of IP addresses, there is nothing to stop someone from implementing a server that uses the DHCP protocol, but does not provide that kind of support.

.August 2009" style="white-space:nowrap;">[citation needed] Effective DHCP-DNS linkage requires having a file of either MAC addresses or local names that will be sent to DNS that uniquely identifies physical hosts, IP addresses, and other parameters such as the default gateway, subnet mask, and IP addresses of DNS servers from a DHCP server.^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ IP address as well as a local network IP address.
  • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

^ If DNS IP servers are not configured for a DHCP client, the client cannot correlate host names to IP addresses.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

.The DHCP server ensures that all IP addresses are unique, i.e., no IP address is assigned to a second client while the first client's assignment is valid (its lease has not expired).^ (Optional) Specifies the IP address of the DHCP client for which bindings will be displayed.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

^ A. Delete the existing IP address leases from the DHCP server.
  • Test4pass 70-216 braindumps download 19 January 2010 18:39 UTC www.myplick.com [Source type: General]

^ The administrator assigns a range of addresses to the DHCP server.
  • DHCP for Windows 2000: Managing the Dynamic Host Configuration Protocol: Chapter 4: Designing a DHCP Infrastructure 19 January 2010 18:39 UTC oreilly.com [Source type: FILTERED WITH BAYES]

.Thus IP address pool management is done by the server and not by a network administrator.^ IP address as well as a local network IP address.
  • electroxcommunica: CREATING A WEB SERVER WITH LINUX, aPACHE, FTP and bind DNS 1 February 2010 7:44 UTC rabinkafle.blogspot.com [Source type: Reference]

^ The DHCP server manages the IP address space of networks directly connected to that server.
  • Part IV Dynamic Host Configuration Protocol (TCP/IP and Data Communications Administration Guide) - Sun Microsystems 1 February 2010 7:44 UTC docs.sun.com [Source type: Reference]

^ Specifies the IP address of a DNS server.
  • Cisco IOS DHCP Server - Cisco Systems 19 January 2010 18:39 UTC www.cisco.com [Source type: Reference]

See also

References

  1. ^ In Unix-like systems this client-level refinement typically takes place according to the values in a /etc/dhclient.conf configuration file.
  2. ^ The TCP/IP Guide - Security Issues

External links


Citable sentences

Up to date as of December 10, 2010

Here are sentences from other pages on Dynamic Host Configuration Protocol, which are similar to those in the above article.








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