IP Address

The Internet Protocol also has the task of routing data packets between networks, and IP addresses specify the locations of the source and destination nodes in the topology of the routing system. For this purpose, some of the bits in an IP address are used to designate a subnetwork. (In CIDR notation, the number of bits used for the subnet follows the IP address. E.g. 208.77.188.166/24) An IP address can be private, for use on a LAN, or public, for use on the Internet or other WAN.

With the development of private networks and the threat of IPv4 address exhaustion, a group of private address spaces was set aside by RFC 1918. These may be reused by anyone. They are often used with network address translators to connect to the global Internet.

The Internet Assigned Numbers Authority (IANA) manages the global IP address space. IANA works in cooperation with five Regional Internet Registries (RIRs) to allocate IP address blocks to Local Internet Registries (Internet service providers) and other entities.