Lab: Active directory network not resolving IPv4 address to names

Rightio so an interesting issue that I'm trying to solve.

I've got a test lab running involving Windows Server 2012 R2s and exchange servers using the trial timeframes.

I have the following:

dc1.domain.com
dc2.domain.com
mbx1.domain.com
mbx2.domain.com

I also have a few others but they're not important here.

Until this week, I have had full internal name resolution fine, so searching for mail.domain.com took me to the load balancer which then round-robined to an exchange server. External names e.g. www.google.com load fine, although they take a little while to resolve and start loading.

Now, if I try and go to an internal address I get an error that it can't connect from the browser as if the address wasn't available. If I ping the server, again it gets a host unreachable. IPv6 connects fine and can resolve names using ping -6 mbx1.domain.com

The only thing I changed was moving the FMSO roles and associated ones back over to dc1 as they where sitting on dc2 and my OCD had kicked in... This was done about a week previous; apart from that everything has been stable for around a month!

What direction should I check to see what is broken? I'm happy to dig around as this is not a production level setup, I'm just having fun tinkering!

Cheers,

chris

Have you set up DNS forwarding to an external DNS server?

Hmmm... seems that my DCs are messed up. I've rebooted dc2 and that appears to be controlling everything even though the FMSO roles where transferred to dc1... its all back up now but very strange... sorting active directories are a dark art I feel!