Hyper-V 2012 R2: Unable to connect to guest.

I’m in two minds whether to write about this one as I should never have missed it, but as the resolution is so simple and its a  real “really” moment, I thought I’d share…

… Anyhow, when trying to connect to a Microsoft Hyper-V hosted VM, you’re asked to log in, enter your credentials and get the cryptic message:

Remote Desktop Connection
A certification authority could not be contacted for authentication. If you are using a Remote Desktop Gateway with a smart card, try connecting to the remote computer using a password. For assistance, contact your system administrator or technical support.
(I would add a screenshot, but Google have been playing again and broken the upload picture feature!!).

Microsoft go on to talk about a solution for SCVMM here, resulting in a requestable Hotfix for 2003 domains available from here. KB939820.
I also see event ID’s 4625, Audit Failures pertaining to Kerberos on the Hyper-V host.

I’m running the free Hyper-V 2012 R2 CORE edition, therefore there is no GUI to speak of.
The issue was caused by me negating to add the DNS server settings on the Hyper-V server.
  1. Connect to the Hyper-V host from either RSAT / RDP or directly.
  2. If the “start menu” is not visible, it can be started by entering the following command: cmd.exe /k C:\Windows\System32\sconfig.cmd
  3. To set DNS, type 8, {Index # of NIC}.
  4. At this point, you’ll see there is no entry next to “Preferred DNS Server”.
  5. Type 2 and enter your preferred DNS server IP.
  6. Click OK to the “Preferred DNS server set”.
  7. Enter your alternate DNS server or press enter to leave blank.
  8. Return to the console and flush DNS.
  9. You should now be able to connect to the guest.

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