If your network is like ours (and I hope that it is not), your DNS server is happily accepting IPv6 address registrations, but your routers can’t makes heads or tails of all those packets with those long addresses on them. Is this a problem? You betcha’.
If a client (Windows Server 2008, Vista, or really just about any recent-vintage Linux distro) is configured to use IPv6 by default, and it is fortunate enough to find an IPv6 address registered in DNS for a server to which it is attempting to connect, guess which protocol it will use to connect to the server? But what if your router can’t pass IPv6 traffic? If you happed to be using a Vista client, it appears that after a few seconds, we fall back on IPv4. However, my Server 2008 RC0 clients are timing out and failing to connect to each other. Bummer!
Rather than going though the impossible process of fixing IPv6 on campus, I have decided to kill IPv6 on my Server 2008 systems. Here is where I got my information:
The instructions are for Vista, but they work on Server 2008, too. I just set this registry DWORD:
to Hexidecimal 0xFF, thus disabling all IPv6 on the server. A quick reboot forced the server to re-register all DNS entries, thus making IPv6 go away. Voila, we are back in business (and RDP connections to my new servers from Vista clients are working much more smoothly).