These 128–bit IPv6 addresses provide greater address space than is available with IPv4. IPv6 addresses are presented as eight groups of four hexadecimal digits, each group separated by a colon. Leading zeros in each group can be suppressed. One or more consecutive groups of all zeros can be replaced by a double colon, as shown in the following example:
As with IPv4 addresses in CIDR format, IPv6 addresses are classless and use prefixes to designate the portion of the address that defines the site's network, as shown in the following example:
For details about IPv6 addressing, see IP Version 6 Addressing Architecture.