nternet Assigned Numbers Authority

The Internet Assigned Numbers Authority (IANA) is the entity that oversees global IP address allocation, DNS root zone management, and other Internet protocol assignments. It is operated by 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 made to assume the responsibility under a United States Department of Commerce contract.

IANA's Responsibilities

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. It maintains a close liaison with the IETF and RFC Editor in fulfilling this function.

In the case of relatively high-profile subsets of protocol numbers - namely IP addresses and domain names, extra policy and handling is required and the allocation process is handled in more specific methods. This is to cope with the multi-layered administration of these resources.

IP addresses

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 co-ordinated globally.

IANA delegates the allocation of IPv4 addresses to RIRs in large chunks (typically in the size of "/8", or 2²⁴ addresses, or more at a time), and the RIRs then subsequently re-allocate smaller chunks in the regions to ISPs and other organizations.

There is also a process for the delegation and allocation of IPv6 addresses, but there is currently little delegation pressure on blocks of IPv6 addresses, as supply vastly exceeds demand.

Domain names

IANA administers the data in the root nameservers, which is the top of the hierarchial DNS tree. This task involves liaising with top-level domain operators, as well as root nameserver operators, and ICANN's policy making apparatus.

It also operates the .int registry for intergovernmental organisations, the .arpa zone for protocol administration purposes, and other critical zones such as root-servers.net.

Protocol parameters

IANA administers those parameters of IETF protocols for which in the middle registry is necessary. Examples include the names of URI schemes and of character encodings approved 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