Used to seeing IPv4 addresses of the form 192.168.1.123? Well, if you thought that was difficult to remember, hold on to your hat! IPv6 addresses are going to be a bit more difficult.

As mentioned in the article above, IPv4 addresses are 32 bits in length, and commonly presented as four decimal numbers in the range 0-255 separated by dots.

IPv6 addresses are 128 bits in length, which means there are sixteen numbers to remember! So a typical IPv6 address might look like 128.91.45.157.220.40.0.0.0.0.252.87.212.200.31.255, if expressed in the old IPv4 dotted decimal notation.

But there are several other changes. The dots are gone in favour of colons. And instead of decimal numbers, there are hexadecimal numbers in the range 00-FF. Further, numbers are grouped into bunches of four digits (which corresponds to 16 bits each).

So correctly expressed, the above address might be 805B:2D9D:DC28:0000:0000:FC57:D4C8:1FFF. I say ‘might be’ because the IPv6 notation permits two further simplifications: zero suppression and compression. Zero suppression works just like in decimal – leading zeroes can be omitted. This would reduce the above address to 805B:2D9D:DC28:0:0:FC57:D4C8:1FFF. Zero compression allows consecutive groups of zeroes to be replaced with two colons. So, in its final form, the above IPv6 address looks like: 805B:2D9D:DC28::FC57:D4C8:1FFF. Easy, huh?