IANA: definition

IANA, the Internet Assigned Numbers Authority, keeps the public lists that make internet names, addresses and technical codes mean the same thing everywhere. It applies rules written by others; it does not make them. Since 1 October 2016 an ICANN affiliate called PTI does this work, with no United States government approval step.

What IANA is

For the internet to work as one network, each domain name A readable internet name made of labels separated by dots. Full definition of domain name and IP address must belong to a single party, and all software must read protocol codes the same way. IANA maintains the authoritative public registry The central database and system of a top-level domain, or loosely the organization that runs it. Full definition of registry that record these assignments.

The role is a public service: the registries are openly published and the services are free. IANA calls itself a neutral steward. It does not set the policies for its registries; it implements those developed by the communities each registry serves. It does not decide which TLDs should exist.

The work goes back to the record-keeping of the first network experiments in the 1970s. Today “IANA” names the functions; the organisation that performs them is Public Technical Identifiers (PTI).

The three IANA functions: names, numbers and protocol parameters

Names. IANA manages the DNS root zone, the top of the naming hierarchy. It assigns the manager of each TLD, records the technical delegation data and publishes the Root Zone Database. Policy comes from ICANN, mainly through the GNSO Generic Names Supporting Organization The ICANN body that develops policy for generic top-level domains. Full definition of GNSO for generic names and the ccNSO Country Code Names Supporting Organization The ICANN body where ccTLD managers develop global ccTLD policy. Full definition of ccNSO for country codes.

Numbers. IANA coordinates IP addresses and the autonomous system (AS) numbers used to route traffic. It allocates large pools of addresses to the five RIR Regional Internet Registry One of five regional bodies that distribute IP addresses, separate from domain registries. Full definition of RIR (AFRINIC, APNIC, ARIN, LACNIC and RIPE NCC), not to internet service providers or end user A buyer who wants a domain to use it, not to resell it. Full definition of end user, except in special cases. Global number policy comes from the RIR communities and is ratified through ICANN’s Address Supporting Organization (ASO). RIRs handle numbers, not domain names.

Protocol parameters. These are the codes and numbers used inside internet protocols. Under RFC Request for Comments A numbered document in the series recording the internet's technical standards and practices. Full definition of RFC 2860 (June 2000), IANA assigns them only as RFCs direct.

IANA, PTI and ICANN: how they fit

PTI is a California nonprofit public benefit corporation formed in 2016. ICANN is its sole member, and PTI’s only purpose is to deliver the IANA functions. Its board combines directors appointed by ICANN and directors drawn from the community.

ICANN holds the obligations and subcontracts the work to PTI, with one agreement per function:

names: the ICANN–PTI Naming Function Agreement, which sets service levels for root zone management The process of checking, applying and publishing changes to the list of all TLDs. Full definition of root zone management;
protocol parameters: a memorandum of understanding between ICANN and the IETF Internet Engineering Task Force The open body that writes internet standards such as DNS, EPP and RDAP. Full definition of IETF, plus annual agreements;
numbers: a service level agreement (SLA) between ICANN and the five RIRs.

The ICANN Bylaws ICANN's main rulebook, which sets its mission, structure and accountability rules. Full definition of ICANN Bylaws add safeguards. Changes to PTI’s articles of incorporation need the approval of the Empowered Community The body that lets ICANN's community groups enforce powers over the Board. Full definition of Empowered Community, and fees charged by PTI under the naming contract must be based on its direct costs.

Stewardship transition of 2016

ICANN has performed the IANA functions since 1999. From 2000 to 2016, a contract with the NTIA National Telecommunications and Information Administration The United States government agency for internet policy, which oversaw IANA until 2016. Full definition of NTIA, part of the United States Department of Commerce, governed how. Under it, United States government approval was a mandatory step for root zone change requests.

In March 2014 the NTIA set criteria for ending this role and asked ICANN to convene the global multistakeholder community. The community wrote proposals to replace the NTIA’s stewardship and strengthen ICANN’s accountability; they met the criteria and were approved.

The last IANA functions contract lapsed on 30 September 2016, and the transition was completed on 1 October 2016. That day PTI began performing the functions, with the same staff and the same website, www.iana.org. New accountability rules came into force at the same time, giving the community direct recourse when it disagrees with ICANN or its Board.

The Affirmation of Commitments A 2009 agreement between ICANN and the United States government, formally ended in 2017. Full definition of Affirmation of Commitments, a 2009 agreement between ICANN and the Department of Commerce, had required regular community reviews of ICANN. Once those reviews had moved into Article 4 of the ICANN Bylaws, ICANN and the NTIA ended it by mutual agreement on 6 January 2017. The NTIA stayed in ICANN as the United States member of the GAC Governmental Advisory Committee ICANN's committee of governments that advises the Board on public policy. Full definition of GAC.

Who checks IANA’s work

Customer Standing Committee The committee that monitors how well the IANA naming function is performed. Full definition of Customer Standing Committee (CSC Corporation Service Company An American business services company whose brand unit is a major corporate registrar. Full definition of CSC). Every month it checks PTI’s naming performance against the service levels in the naming contract and publishes its findings. It can ask for problems to be fixed and escalate them to the ccNSO and GNSO, but cannot start a special review itself. Under the Bylaws as of October 2026, it has two gTLD generic top-level domain A top-level domain not tied to a country, run under ICANN contracts. Full definition of gTLD registry representatives, two ccTLD country code top-level domain A top-level domain for a country or territory, usually two letters long. Full definition of ccTLD representatives and one PTI liaison.
IANA Naming Function Review (IFR). The first was due by 1 October 2018; under the same Bylaws, the next ones follow at least every five years, with special reviews possible.
Separation, as a last resort. PTI can be replaced as naming operator only if an IFR recommends it, supermajorities of the ccNSO and GNSO Councils approve, the public is consulted and the ICANN Board ICANN's board of directors, which adopts policies and approves key decisions. Full definition of ICANN Board agrees.
Other checks. The Root Zone Evolution Review Committee (RZERC) reviews proposed architectural changes to the root zone. The RIRs and the IETF review the number and protocol functions.

As of October 2026, IANA reports meeting 100% of its service levels in all three functions from June to August 2026; its weakest naming month in the previous year was December 2025, at 94%.

A worked example: a ccTLD manager The organization that runs a country code top-level domain. Full definition of ccTLD manager wants to change its TLD’s name server A server that holds a domain's DNS records and answers lookups. Full definition of name server in the root zone. It submits the change through IANA’s online interface for TLD managers. No United States government approval applies, and PTI’s handling counts toward the service levels the CSC reviews each month.

IANA