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Internet Assigned Numbers Authority (IANA)

The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet Protocol-related symbols and Internet numbers.

Currently it is a function of ICANN, a nonprofit private American corporation established in 1998 primarily for this purpose under a United States Department of Commerce contract. Before it, IANA was administered principally by Jon Postel at the Information Sciences Institute (ISI) of the University of Southern California (USC) situated at Marina Del Rey (Los Angeles), under a contract USC/ISI had with the United States Department of Defense. Following ICANN’s transition to a global multistakeholder governance model, the IANA functions were transferred to Public Technical Identifiers, an affiliate of ICANN.

In addition, five regional Internet registries delegate number resources to their customers, local Internet registries, Internet service providers, and end-user organizations. A local Internet registry is an organization that assigns parts of its allocation from a regional Internet registry to other customers. Most local Internet registries are also Internet service providers.


IANA is broadly responsible for the allocation of globally unique names and numbers that are used in Internet protocols that are published as Request for Comments documents. These documents describe methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems. IANA 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 is responsible for assignment of Internet numbers which are numerical identifiers assigned to an Internet resource or used in the networking protocols of the Internet Protocol Suite. Examples include IP addresses and autonomous system (AS) numbers.

IP addresses

: IPv6 Prefix Assignment mechanism with IANA, RIRs, and ISPs.

IANA delegates allocations of IP address blocks to regional Internet registries (RIRs). Each RIR allocates addresses for a different area of the world. Collectively the RIRs have created the Number Resource Organization formed as a body to represent their collective interests and ensure that policy statements are coordinated globally.

The RIRs divide their allocated address pools into smaller blocks and delegate them to Internet service providers and other organizations in their operating regions. Since the introduction of the CIDR system, IANA has typically allocated address space in the size of /8 prefix blocks for IPv4 and /23 to /12 prefix blocks from the 2000::/3 IPv6 block to requesting regional registries as needed. Since the exhaustion of the Internet Protocol Version 4 address space, no further IPv4 address space is allocated by IANA.

Domain names

IANA administers the data in the root nameservers, which form the top of the hierarchical Domain name system (DNS) tree. This task involves liaising with top-level domain “Registrar-of-Record”s, the root nameserver operators, and ICANN’s policy making apparatus.

Since the root zone was cryptographically signed in 2010, IANA is also responsible for vital parts of the key management for the DNSSEC operations (specifically, it is the “Root Zone KSK Operator”). Among other things, this involves regularly holding signing ceremonies where members of a group of Trusted Community Representatives (TCR) physically meet at a predefined location, and go through scripted procedures to generate key material and signing keys. The TCRs can’t be affiliated with ICANN, PTI (an ICANN affiliate) or Verisign because of these organizations’ operational roles in the key management, but are chosen from the broader DNS community. Past and present TCRs include Vinton Cerf, Dan Kaminsky, Dmitry Burkov, Anne-Marie Eklund Löwinder and John Curran.

IANA 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.

Protocol assignments

IANA maintains protocol registries in tables of protocols and their parameters and coordinates registration of protocols. As of 2015 there were over 2,800 registries and subregistries.

Time zone database

The IANA time zone database holds the time zone differences and rules for the various regions of the world and allows this information to be mirrored and used by computers and other electronic devices to maintain proper configuration for timekeeping.

IANA assumed responsibility for the database on October 16, 2011, after the Astrolabe, Inc. v. Olson et al. decision caused the shutdown of the FTP server which had previously been the primary source of the database.