Microsoft has included IPv6 in its operating systems since NT 4.0; it just was not enabled by default. Windows 7 natively supports both IPv4 and IPv6 (as did Vista). The main differences you will notice between IPv4 and IPv6 is the format and size of the IP address. IPv6 addresses are 128 bits (IPv4 is 32 bits) and typically written as eight groups of four hex characters. IPv4, as you saw earlier, is four decimal representations of 8 bits. Each of the eight groups of characters is separated by a colon. An example of a valid IPv6 address is 2001:4860:0000:0000:00 12:10FF:FECD:00EF.

Leading zeroes can be omitted, so you can write the example address as 2001:4860:0:0:12:10FF:FECD:EF. Additionally, a double colon can be used to compress a set of consecutive zeroes, so you can write the example address as 2001:4860::12:10FF:FECD:EF. The IPv6 address is 128 bits; when you see a double colon, it's a variable that says fill enough zeros within the colons to make the address 128 bits.