IPv4 Addressing

Addresses within an internet consist of a network number and a local address. The unique network number is assigned to each network when it connects to another internet. If a local network is not going to connect to other internets, any convenient network number is assigned.

Hosts that exchange packets on the same physical network should have the same network number. Hosts on different physical networks might also have the same network number. If hosts have the same network number, part of the local address is used as a subnetwork number. All host interfaces to the same physical network are given the same subnetwork number.

An internet can provide standards for assigning addresses to networks, broadcasts, and subnetworks. Examples of these standard formats are described in the following sections.