We already know that disabling IPv6 on a 2008 & Exchange 2007 server breaks things but what if we go IPv6 only?
IPv6 Only Domain Controllers:
The installation didn’t cause any trouble but after initially logging on and running a DCDiag we see this:
It turns out that the install of the DNS Server had set the NIC’s properties to be ::1 but the DNS Server was only listening on the Static Site Local address FEC0::2 and its self assigned Link Local. This of course caused all DNS reliant checks to fail and cause a whole world of pain.
Changing the NIC DNS properties to FEC0::2 resulted in a different set of errors:
There were actually 10′s of the System Log errors which made me panic for a bit till I remembered that this is expected behaviour. The expected behaviour is that if there are any Warnings or other bad apples in the Event logs DCDiag will throw some unfriendly errors.
These errors appear to be even more unfriendly owing to a bug in how the Event Viewer copes with IPv6 address.
A quick purge or the Event logs later and we are back in business:
Preparing the Exchange Server
Exchange 2007 has several prerequisites that need to be installed before Setup can be successfully launched. First I’ll add the prerequisites that don’t affect / require a machine to be bound to a domain, if they install correctly then I’ll bind it to the domain (and see how that goes) and finish off with the prerequisites that require a machine to be bound to the domain.
Installing the non-domain related roles / features went smoothly:
Unfortunately binding to the domain was not as smooth:
The first issue to resolve is whether Windows Server 2008 actually wants a A record or whether someone just hasn’t got round to updating the error dialog.
Firing up the NSLookup tool we see that [despite some timeouts (??)] DNS is working as expected. Although this was evident because the SRV lookups for the domain resulted in the name of the Domain Controller.
So I did what every curious Windows Admin knows might fix the problem, do it again. And who’d have guessed it?
Hmm, well with that sorted and following a quick reboot its time to see if the final prerequisite piece of the puzzle works:
Excellent!
There are a few errors but these may not be show stoppers.
Onto the next stage!
Installing Exchange 2007 on an IPv6 Only 2008 Server
Well unfortunately we’ve stumbled at the first hurdle:
The link the error mentions tells us the following:
IPv6 is only supported in Exchange 2007 SP1 when it is installed on a Windows Server 2008 computer that has both IPv4 and IPv6 enabled. If you disable the IPv4 protocol, Exchange 2007 SP1 can't support IPv6.
Well screw that, the Install button hasn’t greyed out so onwards to Victory!
Setup claims to have installed, lets see if the SMTP element is contactable:
Using Exchange 2007 in a Native IPv6 Environment
OWA worked without any major hassles and sending internal email worked fine. Unfortunately trying to send email to an ‘external’ host resulted in a “451 4.4.0 DNS Query Failed”.
Looking through the Event Logs I found this:
Running the suggested powershell command did indeed show that no DNS Servers were set:
No matter what I did using netsh or the NIC GUI the error remained, I resorted to setting the DNS entries in the Hub Transport server properties:
We now get another error but hey at least its progress:
451 4.4.0 primary target IP address responded with "421.4.4.2 unable to connect."attempted failover to alternate host, but that did not succeed.Either there are no alternate hosts, or delivery failed to all alternate hosts.
Turns out I forgot to make the Postfix server listen on its IPv6 address :/ A few quick config changes later and Victory is mine!
Conclusion
Well its a bit painful to get going but it appears to work once setup. I’ll keep this going with some scheduled in and out email to see if it dies after a week or so.