SixOrNot is a Firefox extension which makes it easy for you to identify when the website you're connecting to supports the current generation Internet Protocol (version 6). It also allows you to see a list of all the servers contacted to load a page, along with the IP address your browser connected to to do so. DNS information about each server is also available so that you can see if a site could potentially be loaded via IPv6.

The SixOrNot icon can be displayed via an address bar icon or a button (which may be placed wherever you like in the Firefox UI). The icon indicates whether the main domain of the site you are viewing supports IPv6 and whether your browser used IPv6 to connect to it. SixOrNot looks at each connection Firefox makes and notes whether it was made using IPv4 or IPv6, the information is then displayed via a handy tooltip. SixOrNot also detects the IP address(es) of your local machine for informational display.

Documentation for SixOrNot used to be here, but it's now included within the addon.

Download SixOrNot from: