Best Practice - IPv6 Turn Off? Windows 2008 (and R2) Servers

Question

Hi,
I work for a large organization.  We have close to 10,000 servers globally.  A question has come up if we should disable IPv6 on our Windows 2008 servers.  Our network is not yet capable of using IPv6.
It seems like you have to go out of your way to disable IPv6; therefore, I would assume that it is best to leave IPv6 turned on.
Does anyone have any thoughts about this.  It would be most helpful to have links to pros/cons - best practice.
Thank you.

Answer 1

No, do not disable IPv6. There is no reason to do so unless you have a very specific application issue which is highly unlikely (although there are a few documented ones out there).
http://blogs.technet.com/b/ipv6/archive/2007/11/08/disabling-ipv6-doesn-t-help.aspx
http://blogs.technet.com/b/jlosey/archive/2011/02/02/why-you-should-leave-ipv6-alone.aspx
Jason | http://myitforum.com/cs2/blogs/jsandys | Twitter @JasonSandys
Whoever marked this as an "answer" obviously doesn't remember that bad-old-days of "Everything's on by default! It just works!!" and the billions of dollars in lost productivity that ensued from the hundreds (thousands?) of exploits that followed this
painfully short-sighted decision. You'd think Microsoft would have learned their lesson from the "IIS is on by default!" debacle, but that doesn't seem to be the case.
Best practices for system administration say "turn off the services and protocols you don't use." As such,
IPv6 should ALWAYS be disabled on servers and business workstations if you're not currently using it, just like any other protocol or service you haven't implemented or aren't using. Not using FTP? Don't install or enable
an FTP server. Not using IPv6? Why would you have IPv6 enabled? Just because IPv6 is the newest, shiniest thing on the block doesn't mean you have to use, and it definitely shouldn't require you to start hacking about in the registry to turn it off.
The only exception to this rule would be laptops or mobile devices where the user might (conceivably) take them into an IPv6 environment. Even then, though, you have to balance the "convenience" of not having to switch-on IPv6 against the risk that
your unconfigured IPv6 stack might be exploitable by nefarious patries. Even so, the fact that almost nobody has switched their internal networks to IPv6 means that turning it off on laptops is still probably a "good idea." 
For example, my laptop wireless interface might make sense to leave IPv6 enabled--I don't have any idea when I'll walk into an environment that uses IPv6 and want to use my wireless. But in the office when I'm hard-connected? We don't use IPv6 so it needs
to be "off." Even if it's just a bit of code in the Windows firewall that can be used to say "just reject IPv6 traffic on x interface" is still a big improvement. An absolute home-run would be the addition of logic that allows Windows to dynamically disable
IPv6 when there aren't any NICs or WNICs that are allowed to use it.
Finally, none of this should be construed to mean I'm advising against implementing IPv6, because I'm not. However, like any major technology project you should plan carefully, making sure you understand ALL of the consequences (not just the marketing hype,)
and making sure you'll be able to administer the changed environment as well as your administer the current one. You definitely should not let a vendor (of all things) force the decision to use it upon you because it's "on by default."