I am running Windows server 2003 and my Firefox browser keeps using IPv4 instead of IPv6. Well at least http://ipv6-test.com/ says that my browser uses IPv4. How can I force it to prefer IPv6 over IPv4?
If you have IPv6 access (usually from your internet provider) then Windows 2003 will use it. If the test says you don't have IPv6 then you should probably talk to your ISP.
PS: in Windows 2003 you have to install the IPv6 driver manually. I assumed you already did that.