IPv6 address introduction
In the example, h is a hexadecimal digit 1 through 0, A through F. This is sometimes called colon hexadecimal format.
Depending on the application, you can enter or display an IPv6 address using a shortened version when successive fields contain all zeros (0). You can use two colons (::) and omit leading zeros in a field. (The use of two colons to represent successive zero fields can be used only once in an address.) The following is an example IPv6 address:
IPv6 addresses are often specified by a prefix that identifies a fixed value associated with the first part of the address, followed by a prefix length that specifies the number of bits in the prefix. In IPv6 addressing, a prefix length of 64 typically specifies a network or subnet. A prefix with a prefix length less than 64 typically identifies a portion of the IPv6 address space or a route.
IPv6 addresses do not use subnet masks as in IPv4 formats. Instead, the prefix length can specify an entire network/subnet, or the network portion of a complete host address, as in the following example:
For a more thorough discussion of IPv6 address formats and types, see the Internet Engineering Task Force (IETF) IPv6 RFCs, or see the documentation supplied with your IPv6-supported system or router.