The Internet Assigned Numbers Authority (IANA) is the entity that oversees global IP address allocation, root zone management for the Domain Name System (DNS), media types, and other Internet Protocol related assignments. It is operated by the Internet Corporation for Assigned Names and Numbers, better known as ICANN.
Prior to the establishment of ICANN for this purpose, IANA was administered primarily by Jon Postel at the Information Sciences Institute at the University of Southern California, under a contract USC/ISI had with the United States Department of Defense, until ICANN was created to assume the responsibility under a United States Department of Commerce contract.
IANA is broadly responsible for the allocation of globally-unique names and numbers that are used in Internet protocols that are published as RFC documents. These documents describe methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems. IANA also maintains a close liaison with the Internet Engineering Task Force (IETF) and RFC Editorial team in fulfilling this function.
In the case of the two major Internet namespaces, namely IP addresses and domain names, extra administrative policy and delegation to subordinate administrations is required because of the multi-layered distributed use of these resources.
IANA delegates local registrations of IP addresses to Regional Internet Registries (RIRs). Each RIR allocates addresses for a different area of the world. Collectively the RIRs form part of the Number Resource Organization formed as a body to represent their collective interests and ensure that policy statements are coordinated globally.
IANA delegates the allocation of IP addresses to RIRs in large blocks. The RIRs sub-allocate smaller blocks in their regions to Internet service providers and other organizations. Since the introduction of the CIDR system, IANA typically allocates address space in the size of '/8' prefix blocks for IPv4 and '/12' prefix blocks for IPv6 from the 2000::/3 block to requesting regional registries as needed.
IANA administers the data in the root nameservers, which form the top of the hierarchical DNS tree. This task involves liaising with top-level domain operators, the root nameserver operators, and ICANN's policy making apparatus.
ICANN also operates the .int registry for international treaty organizations, the .arpa zone for Internet infrastructure purposes, including reverse DNS service, and other critical zones such as root-servers.net.
IANA administers many parameters of IETF protocols. Examples include the names of Uniform Resource Identifier (URI) schemes and character encodings recommended for use on the Internet. This task is undertaken under the oversight of the Internet Architecture Board, and the agreement governing the work is published in RFC 2860.
IANA is managed by the Internet Corporation for Assigned Names and Numbers (ICANN) under contract to the United States Department of Commerce (DOC). The Department of Commerce also provides an ongoing oversight function, whereby it verifies additions and changes made in the root to ensure IANA complies with its policies.
On January 28, 2003 the Department of Commerce, via the Acquisition and Grants Office of the National Oceanic and Atmospheric Administration, issued a notice of intent to grant ICANN the IANA contract for three more years. It invited alternative offerors to submit in writing a detailed response on how they could meet the requirements themselves. Such responses were to be received no later than 10 days following publication of the invitation and the decision on whether to open the "tender" to competition was to remain solely within the discretion of the government.
In August 2006, the U.S. Department of Commerce extended its IANA contract with ICANN by an additional five years, subject to annual renewals.
Since ICANN is managing a worldwide resource, but being controlled by U.S. interests, a number of proposals have been brought forward to decouple the IANA function from ICANN. However, it is widely believed that it would be impractical to change the current control structure without risking fracturing the Internet.
IANA was established informally as a reference to various technical functions for the ARPANET, that the Information Sciences Institute performed for the Defense Advanced Research Project Agency (DARPA) of the United States Department of Defense.
The earliest reference to a registry function is probably RFC 322, published on March 26, 1972, in which Vint Cerf and Jon Postel established a "socket registry". This registry was published as RFC 433 in December 1972.
The first reference to the name "IANA" in the RFC series is in RFC 1060, published in 1990, but the function, and the term, was well established long before that; RFC 1174 says that "Throughout its entire history, the Internet system has employed a central Internet Assigned Numbers Authority (IANA)...", and RFC 1060 lists a long series of earlier editions of itself, starting with RFC 349.
In 1996 the "DNS Wars" began as the FNAC ordered the NSF to instruct its contractor, Network Solutions who ran the Internic project, to begin charging for com/net/org domain names. There was widespread dissatisfaction with this concentration of power (and money) in one company and people looked to IANA for a solution. Postel wrote up a draft on the creation of new top level domains.
USC/ISI would not back Postel in the legal sense and IANA, which was a part time "task" had no legal personality - it could not sign contracts - and there was some resentment in the community at paying IANA large sums of money to add one or two lines to the legacy root zone. Jon was trying to institutionalize IANA.
Postel was threatened by Ira Magaziner when he split the root zone, assuming authority for the entire domain name system in an attempt to repatriate the root to IANA; Jon had plans to add hundreds of new tlds, a plan he had advocated for a while. This would let him do it, however it lasted less than a day.
Jon Postel managed the IANA function from its inception until his death in October 1998. Postel had been given defacto authority to perform the IANA function, as he had always done it in his position at the Information Sciences Institute, under its Department of Defense contract. After his death, Joyce Reynolds, who had worked with him at IANA for many years, managed the transition of the IANA function to ICANN.
Starting in 1988, IANA was funded by the U.S. government under a contract between the Defense Advanced Research Projects Agency and Information Sciences Institute (ISI). This contract expired in April 1997, but was extended to preserve IANA's function.