IP address (networking) (Internet address) The 32-bit number uniquely identifying a node on a network using Internet Protocol, as defined in STD 5, RFC 791. An IP address is normally displayed in dotted decimal notation, e.g. 128.121.4.5.
The address can be split into a network number (or network address) and a host number unique to each host on the network and sometimes also a subnet address. The way the address is split depends on its "class", A, B or C (but see also CIDR). The class is determined by the high address bits: Class A - high bit 0, 7-bit network number, 24-bit host number. n1.a.a.a 0 <= n1 <= 127 Class B - high 2 bits 10, 14-bit network number, 16-bit host number. n1.n2.a.a 128 <= n1 <= 191 Class C - high 3 bits 110, 21-bit network number, 8-bit host number. n1.n2.n3.a 192 <= n1 <= 223 DNS translates a node's fully qualified domain name to an Internet address which ARP (or constant mapping) translates to an Ethernet address. [Jargon File] Last updated: 2006-01-27
