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IANA and IP Addresses

(ETH - Zürich, Switzerland)



- The 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.

IP addresses are distributed hierarchically. At the very top level, the IANA is responsible for the entire set of IP addresses. It allocates blocks of addresses to Regional Internet Registries (RIR). There are five RIRs, each responsible for a part of the world’s geography. For instance, the U.S. and Canada get addresses from ARIN, the American Registry for Internet Numbers. Countries in Europe and the mid-East get addresses from the RIPE Network Coordination Centre. These RIRs in turn allocate blocks of IP addresses to ISPs within their region. Since ISPs are tiered, an ISP may allocate a smaller block of addresses to a lower-tier ISP as well as to a company that subscribes to its services.


- Regional Internet Registry (RIR)

A Regional Internet Registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.

There are five Regional Internet Registries (RIRs) in the world. RIRs manage, distribute, and register Internet number resources (IPv4 and IPv6 address space and Autonomous System (AS) Numbers) within their respective regions. These RIRs are:

  • ARIN (Canada, United States, some Caribbean nations) 
  • RIPE NCC (Europe, Russia, Middle East, Central Asia) 
  • APNIC (Asia-Pacific region) 
  • LACNIC (Latin America, some Caribbean nations) 
  • AFRINIC (Africa)


- The NRO

The Number Resource Organization (NRO) was established in 2003 as a coordinating body for the five Regional Internet Registries (RIRs) to act on matters of global importance to all five RIRs, to participate in global Internet governance activities and to coordinate joint projects across the global RIR system. Find out more.


- Local Internet Registry

A Local Internet registry (LIR) is an organization that has been allocated a block of IP addresses by a RIR, and that assigns most parts of this block to its own customers. Most LIRs are Internet service providers, enterprises, or academic institutions. Membership in a regional Internet registry is required to become a LIR.



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