Most common IP addresses and subnet masks share the same IPv4 formatting. An IPv4 address is a 32-bit number represented in four groups of three-digit numbers, known as octets, separated by periods. Each octet has a value between 0 and 255. An IPv6 address is a 128-bit number that's presented in eight groups of four-digit hexadecimal numbers separated by colons. This allows for a huge range of addresses, and as a result IPv6 addressing essentially includes subnet information.