Exchange installed on Win2008 GC DC ADAccess Discovery issues

I’ve recently come across a problem where my exchange 2007 environment would stop sending and receiving mail if the main domain controller was offline, after we had some trouble with the PDC.  If you restarted the exchange box, exchange would fall over and nothing would start, leaving you with an event log riddled with exchange startup errors.

Exchange is installed on a GC domain controller, and I couldn’t figure out why exchange couldn’t see it, as replication etc was fine between domain controllers.

 

I started investigating and the MSExchange ADAccess service reported the following:

Process MAD.EXE (PID=2916). Exchange Active Directory Provider has discovered the following servers with the following characteristics:
(Server name | Roles | Enabled | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data | Netlogon | OS Version)
In-site:
hrcptws001.mydomain.local CDG 1 7 7 1 0 1 1 7 1
HRCPTWS002.mydomain.local CDG 1 0 0 1 0 0 0 0 0
HRCPTWS003.mydomain.local CDG 1 7 7 1 0 1 1 7 1
Out-of-site:

This was a problem for me, as the exchange was installed on HRCPTWS002, and this told me that it was not reachable, and it wasn’t going to use it as a config server.

After a good couple of hours of troubleshooting Active Directory, I found that it was a pretty simple

IPv6 was disabled on the network card…

For some reason, exchange wants ipv6, and for some unknown reason, I disabled it when I setup the server.  The only thing I did was enable ipv6 on the network card, restarted the exchange services, and a couple of minutes later my ADAccess service returned a log evevnt that read:

 

Process MAD.EXE (PID=2916). Exchange Active Directory Provider has discovered the following servers with the following characteristics:
(Server name | Roles | Enabled | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data | Netlogon | OS Version)
In-site:
hrcptws001.mydomain.local CDG 1 7 7 1 0 1 1 7 1
HRCPTWS002.mydomain.local CDG 1 7 7 1 0 1 1 7 1
HRCPTWS003.mydomain.local CDG 1 7 7 1 0 1 1 7 1
Out-of-site:

Happy Exchange Server.