IPv6: IPv6 address format

Unlike IPv4, which uses a dotted-decimal format with each byte ranges from 0 to 255, IPv6 uses eight groups of four hexadecimal digits separated by colons. For example, this is a valid IPv6 address:

2340:0023:AABA:0A01:0055:5054:9ABC:ABB0

If you don’t know how to convert hexadecimal number to binary here is a table that will help you:

IPv6 address shortening

The IPv6 address given above looks daunting, right? Well, there are two conventions that can help you shorten what must be typed for an IP address:

1. a leading zero can be omitted

For example, the address mentioned above (2340:0023:AABA:0A01:0055:5054:9ABC:ABB0) could be shorten to 2340:23:AABA:A01:55:5054:9ABC:ABB0

2. successive fields of zeroes can be represented as two colons (::)

For example, 2340:0000:0000:0000:0455:0000:AAAB:1121 can be written as 2340::0455:0000:AAAB:1121

NOTE – you can shorten an address this way only for one such occurrence. The reason is obvious – if you had more than occurence of double colon you wouldn’t know how many sets of zeroes were being omitted from each part.

Here is a couple of more examples that can help you grasp the concept:

Long version: 1454:0045:0000:0000:4140:0141:0055:ABBB
Shortened version: 1454:45::4140:141:55:ABBB

Long version: 0000:0000:0001:AAAA:BBBC:A222:BBBA:0001
Shortened version: ::1:AAAA:BBBC:A222:BBBA:1