Hyper-V Replica and Name Resolution

Hyper-V Replica and Name Resolution

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I have been running Hyper-V Replica in my house for a while now.  A while ago I noticed that some of my virtual machines kept on going into a critical replication state.  It took a while for me to figure out what was happening:

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Can you spot the difference between the working virtual machine and the failed one?  The failed virtual machine is replicating using the fully qualified domain name – while the working one is using the short network name.  Looking at the event log for this virtual machine confirmed that something was going wrong with name resolution:

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Now for a confession.  I am a bit of a klutz when it comes to configuring name resolution.  For this reason my initial thought was to just change my virtual machines to all use the short network name for replication.  But there was a problem with this approach.  When you perform a planned failover using Hyper-V Replica we automatically switch to using the fully qualified domain name.

So I bit the bullet and tracked down some colleagues who were able to help me sort out my DNS server – and once that was done Hyper-V Replica was rock solid again.

Cheers,
Ben

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  • Can you detail what the DNS server issues and resolutions were?

  • Plus one for me. I'm having similar issues.

    I have a three node Hyper-V Server Lab and I'm getting name resolution issues - but on the actual Hyper-V Servers. Two out of the three nodes use their FQDNs (ending with .local) the third uses it's short network name.

    The result is I can't move VMs between the nodes, apparently due to authentication/name resolution issues. So your comment of "Sort out my DNS Server" seems to be the answer. The DC in my case is a Server2012 Essentials box, which is also the DNS - with my router as the alt DNS.

    Explaining how you sorted your DNS would be really helpful

  • I'm not seeing any issues with name resolution however I am seeing something much more imposing. Occasionally when starting a new replication the initial Replica will get to about 30 % or so then the main server the VM is on will suddenly crash.  Nothing definitive in the logs either.  

  • Hi Brad,

    as we all IT-Pros have Families as well, what was the Problem in the "DNS" Problem ?

    Regards

    Markus

  • I also wish there was more detail regarding DNS here. I've had a really (REALLY!) hard time with Hyper-V Replica, both Kerberos based (works, but keeps giving up with errors and I have to resume) and Certificate based (couldn't get it set up properly).

    I don't have DNS solutions but I can tell you my symptoms and my workaround.

    Symptoms: when enabling replication, I use an FQDN to specify the Replica Server name and when I click next on the wizard, it turns that FQDN into a simple name (in the example above, user would input HYPER-V-2.armstrong.house, the wizard would change it to HYPER-V-2).

    This is a problem and you should stop until you solve this, or you will get into trouble. I could confirm it on the command line: doing

    ping HYPER-V-2.armstrong.house

    would show the message

    "pinging HYPER-V-2".

    The full name would get dropped because of something in my DNS.

    I worked around this by including this in my c:\windows\system32\drivers\etc\hosts" file:

    10.0.0.1 HYPER-V-2.armstrong.house HYPER-V-2

    Another thing that had me tricked: DNS configuration on your management machine matters. I thought the errors I was seeing had to be fixed on the Hyper-V hosts, but no - I was managing from a VM running a Windows 8 evaluation system; it needed proper DNS configuration too. So, that hosts file workaround is not one any one of the two hosts, it's on the management machine, where you're running Hyper-V manager from.

    I hope this helps someone.

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