Today I came into work to find that none of our users could access their mailboxes. On inspection, I managed to isolate the problem as a DNS issue. When I looked at the Standard Primary DNS Zone on our Domain Controller I was shown a nice big red cross and "The DNS server encountered a problem while attempting to load the zone. The transfer of zone data from the master server failed."Most forums on the Internet give lots of info on secondary zones and how to reconfigure them to reload from the primary zone - in this case the error was with the Standard Primary Zone and as such, no reloading was possible! For some reason, the zone wasn't set up as an Active Directory Integrated (ADI) zone and as such there was no backup of the zone in AD. As soon as I get a chance, this will be rectified and the zone will become an ADI Zone!
In the meantime - how do we go about solving this problem? I looked in the system32\dns folder and opened the domain.local file to see that it was completely empty - this is where our problem is. If the zone is not ADI, this text file is where all the DNS information is stored. There should also be a Backup folder in here, with a copy of all the files. In my case there was a fully populated domain.local file which I was able to copy back into the system32\dns folder and replace the empty domain.local file. A quick restart of the DNS Server service on the server and Hey Presto! DNS is back up and running!
The Exchange server also required a reboot to bring all the services back up and allow all staff members to access the mailboxes once again.
Moral of the story: Make sure your DNS Zone is ADI and backup the system32\dns folder daily!
