How to write an IPv6 address

The appearance of IPv6 addresses differs from IPv4 addresses and you express them differently.

Hexadecimal IPv6 address representations

The 128 bits in an IPv6 address are divided into 8 blocks of 16 bits each.

Following is the preferred IPv6 address format:

XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX

Each 16 bit block in an IPv6 address is converted into a 1 to 4 digit hexadecimal number separated by colons (:).

The format to represent an IPv6 address is n:n:n:n:n:n:n:n, where n is the hexadecimal representation of 16 bits in the address; for example, 2001:0:0:0:0:0:0:43.

Each nonzero field must contain at least one numeral.

Within a hexadecimal field, you do not need leading zeros.

Certain classes of IPv6 addresses commonly include multiple adjacent fields that contain hexadecimal 0.

The sample address—2001::43—includes six adjacent fields that contain zeroes represented by a double colon (::) .

You can use a double colon to compress the leading zero fields in a hexadecimal address.

The system can display a double colon only once in an address.

Four more ways to write an IPv6 address

2001:DB8:0000:0000:25AB:0000:0000:0001
2001:DB8:0:0:25AB:0:0:1
2001:DB8:0:0:25AB::1
2001:DB8::25AB:0:0:1