There are a number of issues that I've seen because of the idiocracy above:
- Slow XP performance on every task when joined to a domain with a 2008 server with IPv6
- Broken SBS 2008 server when you uncheck the box (things that break are "Applying Computer Settings" for a long time, Exchange won't start, Network Icon shows offline in error)
- Exchange 2010 won't install when IPv6 is unchecked (but not disabled)
- Exchange 2007 and Exchange 2010 won't start when unchecked (but not disabled)
- Other "random" issues that can't be pinned down
So basically you have two solutions:
- Implement IPv6 on EVERYTHING - aka get a new switch, router, firewall, etc. that supports IPv6, configure it and everything else with IPv6 (that includes any legacy XP or 2003 boxes in the network), and get it all working. Then you just translate to the IPv4 world for the rest of your internet until everyone jumps on that bandwagon. Oh, and by the way, you'll probably need to replace all your gear before it gets to that point.
- Go the cheap route and completely disable IPv6. I say cheap because it's not only cheaper in hardware (you don't have to replace all your infrastructure just because of IPv6 compatibility - granted, it can give you a good bullet point to show the boss if you want to anyway...), but it's cheaper in labor because you don't have to teach all your geeks (umm, I mean IT professionals...) how to read and understand the new subnets.
Since I'm betting that most people like to go the way of "cheap," I'll detail that one for you :-) If you'd rather go balls-to-the-walls, go for it. Just make sure you understand the animal first.
On your new, shiney Server 2008 / 2008r2, first you want to Uncheck the box that says "IPv6" (DUHH!)
Once that's done, go to Regedit***. You'll want to navigate here:
Create a DWord (32-bit) value named "DisabledComponents" and Click OK. Note: There is no space in the DWord name - and no quotes either ;-)
Double Click you're new "DisabledComponents" DWord and put in the following value to completely disable ALL of IPv6 (except IPv6 loopback interface):
ffffffff --- Hex
4294967295 --- Dec
There are also other options to do with this DWord, as detailed perfectly by MS here:
Once done, restart your server to make sure that everything takes full effect. I've seen it take effect without restart, but restart is always best practice when playing with the registry.
If you have additional servers running 2008 or 2008r2: rinse, lather, repeat.
Now you should have smooth sailing with just IPv4 on the network. And if it's not smooth, at least you know that IPv6 wasn't your problem :-)
Don't go playing with the registry unless you actually know what you're doing.
If you don't know what you're doing in the registry, bad bad things ensue.
If you insist on playing in the registry anyway, you should also go update your resume and notify your boss that they will soon need a replacement that can rebuild a server.
Here's some books that should help out:
Understanding IPv6, Second Edition