I am aware that IANA is a department of ICANN, but how are their roles divided?

IANA should allocate IPv4 and IPv6 addresses to RIR's, allocate AS number ranges to RIR's and administrates the root DNS servers ([a-m].root-servers.net) among other things.

What is left for ICANN? Introducing new TLD's. Something else?


1 Answer 1


The Internet Corporation for Assigned Names and Numbers (ICANN) is a non-profit organisation responsible for the root-level infrastructure, policy and governance of the Internet. Principally they:

  • Work closely with Domain Name Registries that have chosen to enter into a contract with ICANN for governance, technical assistance and dispute resolution etc. (It is not mandatory for registries to come under ICANN, for example .edu and .gov are independently governed).

  • Accredit Domain Name Registrars to allocate Domain Names to organisations and individuals for the Domain Name Registries with which ICANN have a contract in place.

    ICANN --> Registry --> Registrar ( --> ISP )

They have a subsidiary organisation, Internet Assigned Numbers Authority (IANA) which is globally responsible for the management and coordination of:

  • IP addresses and addressing systems - allocating IP addresses (both IPv4 and IPv6) from the pools of unallocated addresses to Regional Internet Registries (RIR's) according to needs, ICANN's global policies, IETF technical standards etc. There are 5 RIR's - AFRINIC (Africa Region), APNIC (Asia/Pacific Region), ARIN (North America Region), LACNIC (Latin America and some Caribbean Islands), RIPE NCC (Europe, the Middle East, and Central Asia). RIR's manage the allocation of IP addresses to National Internet Registries (NIR's), who manage the allocation to Internet Service Providers (ISP's).

  • Autonomous System Numbers, which are used by ISP's for routing Internet traffic, and allocated through the same channels as IP addresses.

  • Protocol Assignments - maintaining the official technical standards as implemented on the Internet, with reserved port numbers and protocol acronyms etc (published as a long list of RFC's).

  • The DNS Root Zone - assignments of Global Top-Level Domains (gTLDs) and Country-Code Top-Level Domains (ccTLDs) to third-party Domain Name Registries. Also the DNSSEC Root Key Signing Key is managed by IANA.

  • Registry service for .int and .arpa zones, which are not available for use by general public.

    IANA --> RIR --> NIR --> ISP

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