Till Windows XP,there was no extended support by default for IPv6,only for IPv4 addresses (those are 32-bit in length like 10.10.1.1,255.255.255.0 and so on).
With Vista comes the in-built support for IPv6 addresses (these are long ones with 128-bit length like 2002:c058:6301::c058:6301)which can’t be removed unlike in XP. So if we want to renew or release dynamic IP addresses depending upon their type like whether they are IPv4 or IPv,we can do that quite easily thanks to the cool set of IPv6 commands that come bundled with the ipconfig tool in Vista.
Finding which commands works with IPv4 or IPv6 in ipconfig is easy.
Go to Start > Run > cmd and in the command prompt,type ipconfig/?.
This will display all associated commands that can be used with ipconfig :
Note the commands with 6 as the suffix – /release6 and /renew6.
These take care of IPv6 addresses in releasing them and reassigning them in case the system takes dynamic IPv6 addresses from a DHCP server.
For dynamic IPv4 addresses,the good old commands – ipconfig/release and ipconfig/renew still hold true,the new command above are only for IPv6 dynamically assigned addresses.