Text representations of IP addresses must conform to the industry standard defined in RFC-2373, IP Version 6 Addressing Architecture. IPv4 addresses and masks must be written in the standard IPv4 dotted-decimal form:

ddd.ddd.ddd.ddd

where ddd is a one-to-three digit decimal number between 0 and 255.

IPv6 addresses must be written in the standard IPv6 form:

x:x:x:x:x:x:x:x

where the xcharacters are the hexadecimal value of the eight 16-bit pieces of the address. For example:

FEDC:BA98:7654:3210:FEDC:BA98:7654:3210
1080:0:0:0:8:800:200C:417A

Due to some methods of allocating IPv6 addresses, it is common for addresses to contain long strings of zero bits. To simplify writing addresses containing zero bits, you can use a special syntax to compress the zeros. You can use two colons (::) to indicate multiple groups of 16-bits of zeros. The double colons (::) can only appear once in an address. They can also be used to compress the leading and/or trailing zeros in an address. For example, the following shorthand addresses can be used:

An alternative form that is sometimes more convenient in a mixed environment of IPv4 and IPv6 nodes is x:x:x:x:x:x:d.d.d.d, where the x characters are the hexadecimal values of the six high-order 16-bit pieces of the address, and the d characters are the decimal values of the four low-order 8-bit pieces of the address (standard IPv4 representation). Some examples follow: