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The Internet Assigned Numbers Authority (IANA) was the central coordinator for the assignment of unique parameter values for Internet protocols. The IANA was chartered by the Internet Society (ISOC) to act as the clearinghouse to assign and coordinate the use of numerous Internet protocol parameters. The IANA was operated at the Information Sciences Institute/University of Southern California under contract with the Department of Defense,

The IANA functions historically included:

(1) The coordination of the assignment of technical Internet protocol parameters;
(2) the administration of certain responsibilities associated with Internet DNS root zone management;
(3) the allocation of Internet numbering resources; and
(4) other services related to the management of the .ARPA and .INT top-level domains.

These functions are discussed in more detail below.

The IANA makes technical decisions concerning root servers, determines qualifications for applicants to manage country code TLDs, assigns unique protocol parameters, and manages the IP address space, including delegating blocks of addresses to registries around the world to assign to users in their geographic area.[1]

The responsibilities encompassed within the IANA functions require cooperation and coordination with a variety of technical groups and stakeholder communities. For example, protocol parameters are developed through and overseen by groups such as the Internet Engineering Task Force (IETF) and the Internet Architecture Board (IAB), policies and procedures associated with Internet DNS root zone management are developed by a variety of actors (e.g., the Internet technical community, ccTLD operators, and governments) and continue to evolve, and policies and procedures related to Internet numbering resources are developed within the RIRs.

On July 2, 2012, The U.S. Commerce Department's National Telecommunications and Information Administration (NTIA) announced that it awarded the Internet Assigned Numbers Authority (IANA) functions contract to the Internet Corporation for Assigned Names and Numbers (ICANN).

Historical background[]

IANA functions were initially performed under a series of contracts between the Department of Defense’s Advanced Research Projects Agency (DARPA) and the University of Southern California (USC), as part of a research project known as the Terranode Network Technology (TNT). As the TNT project and the DARPA/USC contract neared completion, the U.S. Government recognized the need for the continued performance of the IANA functions as vital to the stability and correct functioning of the Internet.

In January 1999, NTIA initiated a procurement process to fulfill this need.[2] NTIA awarded the IANA functions contract to ICANN in February 2000, and subsequently in March 2001, March 2004, and August 2005.[3] The current contract expires September 30, 2011.[4]

IANA functions[]

Coordination of the assignment of technical protocol parameters[]

This function includes the review and assignment of unique values to numerous parameters (e.g., operation codes, port numbers, object identifiers, protocol numbers) used in various Internet protocols. This function also includes dissemination of listings of assigned parameters through various means (including on-line publication) and the review of technical documents for consistency with assigned values.

Administration of certain responsibilities associated with Internet DNS root zone management[]

This function includes receiving requests for and making routine updates of the top-level domain contact, nameserver and DNS record information. This function also includes receiving delegation and redelegation requests, investigating the circumstances pertinent to those requests, and making recommendations and reporting actions undertaken in connection with processing requests.[5] Additionally, this function involves certain responsibilities related to DNSSEC operation at the root, including management of the root zone Key Signing Key (KSK).[6]

Allocation of Internet numbering resources[]

The third function involves responsibilities for allocated and unallocated IPv4 and IPv6 address space and Autonomous System Number (ASN) space, including the delegation of IP address blocks to Regional Internet Registries (RIRs) for routine allocation. This function also includes reservation and direct allocation of space for special purposes, such as multicast addressing, addresses for private networks and globally specified applications.

The IANA maintains registries of names and numbers for use within the Internet in order to avoid duplicate allocation of one of those names or numbers and the consequent confusion and failed interoperability that would arise.

Other services[]

Other services related to the performance of the IANA functions include the management of .ARPA and .INT top-level domains.


  1. “The Internet Assigned Numbers Authority (IANA) is responsible for the overall coordination and management of the Domain Name System (DNS), and especially the delegation of portions of the name space called top-level domains. . . . Applications for new top-level domains (for example, country code domains) are handled . . . with consultation with the IANA.” Name.Space, Inc. v. Network Solutions, Inc., 202 F.3d 573, 583 (2d Cir. 2000)(full-text).
  2. To assist in this transition from the DARPA contract with USC to ICANN, in 1998, ICANN entered into an agreement with the USC Information Sciences Institute (USC/ISI) to transition certain functions, responsibilities, assets, and personnel to ICANN.
  3. Each contract and modifications are available here.
  4. The current contract has an option to extend the performance period for an additional six months. If necessary, NTIA will exercise this option in order to complete the contract procurement process. See Contract Clause 1.5 of the current contract here.
  5. Performance of this function in relation to country code top level domains (ccTLDs) has evolved over time to address specific issues, one of which has been how best to respect the legitimate interests of governments in the management of their respective ccTLD within the current model.
  6. At present, the process flow for root zone management (see diagram) involves three roles that are performed by different entities through two separate legal agreements with NTIA. The process itself includes the following steps: (1) TLD operators submit change requests to the IANA Functions Operator; (2) the IANA Functions Operator processes the request and conducts due diligence in verifying the request; (3) the IANA Functions Operator sends a recommendation regarding the request to the Administrator for verification/authorization; (4) the Administrator verifies that the IANA Functions Operator has followed its agreed upon verification/processing policies and procedures; (5) the Administrator authorizes the Root Zone Maintainer to make the change; (6) the Root Zone Maintainer edits and generates the updated root zone file; and (7) the Root Zone Maintainer distributes the updated root zone file to the thirteen (13) root server operators. Currently, ICANN performs the role of the IANA Functions Operator, NTIA performs the role of Administrator, and VeriSign performs the role of Root Zone Maintainer. NTIA’s agreements with ICANN (IANA functions contract) and VeriSign, Inc. (Cooperative Agreement) provide the process through which changes are currently made to the authoritative root zone file.

See also[]