Reading a Dotted-Decimal Address

An IP address (Internet Protocol address) is a logical number that identifies a device on a network, much like a street address identifies a house. Every device that sends or receives data needs one so packets can find their way to it.

Version 4 of the protocol, called IPv4, uses a 32-bit address. Those 32 bits give just over 4.2 billion possible addresses, which once seemed endless but eventually ran short as the internet grew.

An IPv4 address is split into four groups of 8 bits each. Each 8-bit group is called an octet. Four octets times 8 bits equals the full 32 bits.

Because 8 bits can represent values from 0 to 255, each octet is a number in that range. The familiar form 192.168.1.10 is simply those four octets written as decimal numbers, separated by dots.