The first rule to help reduce the notation of IPv6 addresses is any leading 0s (zeros) in any 16-bit section or hextet can be omitted. For example:
- 01AB can be represented as 1AB
- 09F0 can be represented as 9F0
- 0A00 can be represented as A00
- 00AB can be represented as AB
This rule only applies to leading 0s, NOT to trailing 0s, otherwise the address would be ambiguous. For example, the hextet “ABC” could be either “0ABC” or “ABC0”.
The Figures 1 to 8 show several examples of how omitting leading 0s can be used to reduce the size of an IPv6 address. For each example the preferred format is shown. Notice how omitting the leading 0s in most examples results in a smaller address representation.