In IPv6, addresses are generally longer than in IPv4, as they consist of 128 bits, represented as eight groups of four hexadecimal digits. To facilitate handling and improve readability, there are specific rules that allow the representation of these addresses to be minimized when they contain zeros.

We explain how they can be simplified:

1. Leaving zeros omitted

• In any sequence of numbers within an IPv6 address, the leading zeros of each group (block of four digits) can be omitted. For example:
  
  • 2001:0db8:0000:0000:0000:ff00:0042:8329 can be written as 2001:db8:0:0:0:ff00:42:8329.
    

2. Contraction of blocks of zeros

• If an IPv6 address contains one or more consecutive blocks of all zeros, these blocks can be replaced by colons :: (double colon). This can only be done once in the address to avoid ambiguity. For example:
  
  • 2001:0db8:0000:0000:0000:ff00:0042:8329 can be simplified to 2001:db8::ff00:42:8329.
  • 2001:0db8:0000:0000:0000:0000:0000:0001 can be simplified to 2001:db8::1.
  • 2001:0db8:0000:0000:0000:0000:0000:0000 can be simplified to 2001:db8::.
    

3. Combination of both techniques

• You can combine leading zero omission and block contraction to obtain an even more simplified representation. For example:
  
  • 2001:0db8:0000:0000:0000:ff00:0042:0000 can be written as 2001:db8::ff00:42:0.

These simplifications are especially useful for making IPv6 addresses more manageable in network configuration, in documentation, and when communicating between technical personnel.

Additionally, devices and software applications that work with IPv6 automatically interpret and expand these addresses to their full form when necessary for processing or routing.