Help - IP Addresses
Every machine that is on a TCP/IP network (a local network, or the network of the Internet) has a unique Internet Protocol (IP) address. Networks using the TCP/IP protocol route messages based on the IP address of the destination..
Within an isolated network, such as an office, you can assign IP addresses at random as long as each one is unique. However, connecting to the Internet requires use of a registered IP address (called an Internet address) to avoid duplicates. This may be either a permanent address or one that is dynamically assigned for a dial-up session.
Most machines also have a Domain Name. These are easier for people to remember. e.g. www.ip-lookup.net. Resolution between Domain Names and IP addresses is handled by the network and the Domain Name Servers (DNS).
Currently there are two types of Internet Protocol (IP) addresses in active use: IP version 4 (IPv4) and IP version 6 (IPv6).
IPv4 was initially deployed on 1 January 1983 and is still the most commonly used version. IPv4 addresses are 32-bit numbers often expressed as 4 octets in "dotted decimal" notation (for example, 192.0.32.67).
Deployment of the IPv6 protocol began in 1999. IPv6 addresses are 128-bit numbers and are conventionally expressed using hexadecimal strings (for example, 1080:0:0:0:8:800:200C:417A).
Both IPv4 and IPv6 addresses are assigned in a delegated manner. Users are assigned IP addresses by Internet service providers (ISPs). ISPs obtain allocations of IP addresses from a local Internet registry (LIR) or national Internet registry (NIR), or from their appropriate Regional Internet Registry (RIR).