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