Here's the scenario.
Host machine running Windows 2012 Server R2, all updates installed. Workgroup. Hyper-V installed.
1st Hyper-V machine
Windows 2012 R2 Server. Set as domain controller.
Active Directory Domain Services
File and Storage Services.
System is the DC and hosts user files. Also hosts Quickbooks data file.
2nd Hyper-V machine
Windows Server 2012R2 All updates installed.
Remote Desktop Services
File and Storage services
Web Server (IIS)
Increasingly when user attempt to log into the TServer they'll get the "The specified domain either does not exist or could not be contacted". error. Restarting DNS services on the DC and Tserver seems to resolve the issue temporarily. Ultimately the issue seems to self heal but not after disallowing log on for an unreasonable amount of time. 15 minutes or more. The issue has been occurring with greater frequency.
I'm not a DNS guru. The only resolutions I've found online to this point pertain to Server 2000 and 2003. Not much regarding this issue in 2012R2.