An Internet Protocol (IP) address is a numerical label that is assigned to devices participating in a computer network that uses the Internet Protocol for communication between its nodes.
The designers of TCP/IP defined an IP address as a 32-bit number and this system, known as Internet Protocol Version 4 or IPv4, is still in use today. However, due to the enormous growth of the Internet and the resulting depletion of available addresses, a new addressing system (IPv6), using 128 bits for the address, was developed in 1995 and last standardized by RFC 2460 in 1998.
IPv4 uses 32-bit (4-byte) addresses, which limits the address space to 4,294,967,296 (232) possible unique addresses.
IPv4 addresses are usually represented in dot-decimal notation (four numbers, each ranging from 0 to 255, separated by dots, e.g. 126.96.36.199). Each part represents 8 bits of the address, and is therefore called an octet.
More information about IPv4, please visit Wikipedia: IPv4.
The rapid exhaustion of IPv4 address space, despite conservation techniques, prompted the Internet Engineering Task Force (IETF) to explore new technologies to expand the Internet's addressing capability. The permanent solution was deemed to be a redesign of the Internet Protocol itself. This next generation of the Internet Protocol, aimed to replace IPv4 on the Internet, was eventually named Internet Protocol Version 6 (IPv6) in 1995. Mathematically, the new address space provides the potential for a maximum of 2128, or about 3.403 x 1038 unique addresses.
Example of an IPv6 address:
More information about IPv6, please visit Wikipedia: IPv6 Address.
In Windows the IP address can be determined by using the command-line tool ipconfig. In Unix the command-line ifconfig performs this function.
The IP address corresponding to a domain name can be determined by using nslookup example.net or dig example.net.