What is IANA?

The Internet Assigned Numbers Authority (IANA) is a standards function that oversees the global coordination of the Internet's unique identifiers. It is not a separate organization but a set of responsibilities historically performed by Jon Postel at the University of Southern California's Information Sciences Institute. Since 1998, these functions have been operated by the Internet Corporation for Assigned Names and Numbers (ICANN) under contract with the U.S. National Telecommunications and Information Administration (NTIA), which ended in 2016 with the transition to a multistakeholder model.

IANA's work falls into three main areas: domain names, IP addresses, and protocol parameters. For domain names, IANA manages the DNS root zone, including the root servers and the top-level domains (TLDs). For IP addresses, IANA allocates large blocks of IPv4 and IPv6 address space to the five Regional Internet Registries (RIRs), which then distribute them to local ISPs and organizations. For protocol parameters, IANA maintains registries of numbers used in Internet protocols, such as port numbers (e.g., TCP/UDP ports), protocol numbers (e.g., 6 for TCP, 17 for UDP), and other identifiers like enterprise numbers and MIME types. These registries are essential for interoperability; any new protocol or extension must register its parameters with IANA to avoid conflicts.

IANA sits at the top of the Internet's identifier hierarchy. Its authority derives from community consensus and technical necessity rather than legal mandate. The IANA functions are documented in RFCs such as RFC 2860 (the MoU between ICANN and the IETF) and RFC 7020 (the Internet Numbers Registry System). The IETF, RIRs, and ICANN's supporting organizations collectively govern IANA's policies through open, bottom-up processes. Without IANA, the Internet would lack a single authoritative source for unique numbers and names, leading to fragmentation and conflicts.