The Internet Corporation for Assigned Names and Numbers (ICANN) is a non for profit organisation coordinating the Domain Name System (DNS), Internet Protocol (IP) addresses, space allocation, protocol identifier assignment, generic (gTLD) and country code (ccTLD) Top-Level Domain name system management, and root server system management functions.



The Internet Assigned Numbers Authority (IANA) is responsible for the global coordination of the DNS Root, IP addressing, and other Internet protocol resources such as IP numbers or addresses. IANA manages the global pool of Internet numbers (Internet Protocols IPs and Autonomous System Numbers ASNs) and distributes them among the five regional Internet registries (RIRs).

How are RIRs allocated address space?

The Internet Number Resource blocks allocated by IANA is governed by the following global polices that define their distribution.

  1. Criteria governing the allocation of IPv4 address space from the IANA to the RIRs
  2. Criteria governing the allocation of IPv6 address space from the IANA to the RIRs
  3. Criteria governing the allocation of ASN Blocks from IANA to RIRs


IPv4 Exhaustion

In February 2011, the Internet Assigned Numbers Authority (IANA) allocated the remaining last five /8s of  IPv4 address space to the Regional Internet Registries (RIRs) in accordance with the Global Policy for the Allocation of the Remaining IPv4 Address Space. With this action, the free pool of available IPv4 addresses is now fully depleted. Insert link http://www.icann.org/en/news/in-focus/global-addressing/remaining-ipv4