Thread: There are currently no logon servers available to service the logon request.

I ran into this after installing a backup domain controller for their dual domains with trusts established.

They have a domainA with a Primary and Backup Domain Controller. They also have a domainB with a Primary and a Backup Domain Controller that I had just installed and configured. After a routine install of Windows Update for the two DCs in domainA, calls started flooding in about unable to access network shares. Right after I came back from lunch, what timing.

The situation:
Both DCs in domainA are able to access the Primary DC on domainB but gets the above error when accessing the Backup DC on domainB. So I rebooted the Backup DC on domainB and that seem to have resolved the issue which let the users re-established their network shares. A sigh of relief. But later on, I checked the event viewers and I see the above error is happening again. But only for the DCs in domainA. Users were fine, this could be just cached credentials. I fear that after another reboot of the DCs in domainA, I'm doomed to be here all night for sure. Good thing it's already after work. Time to find the real fix.

After trying to search for some answers online, I found a lot of assumptions of try this or that but nothing concrete. I will fast forward to the fix that I managed to figure out. I just needed to add the zone of domainA into the DNS server of the Backup DC of domainB. An easy way is to enable zone transfers to all the nameservers. Add the backup zone, point to the DNS master in domainA, hit OK and go home and have a cold one.

I wouldn't have known to do this if I didn't try to do a validate trust on my Backup DC of domainB. Because it works fine on the Primary DC of domainB and both DCs on domainA. The error it gave me was "could not locate domain controller for domainA". Bingo! DNS issues.

Enjoy.