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One of the VM instance's network went down i.e it was neither accessible via ssh nor it could communicate with other machine in LAN.

Access was restored when the instance was restarted.

This log was found in syslog " Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP."

Need to know why this happen and workaround to prevent it in future

Edit: Issue is Communication with the VM Instance was down. It was not accessible nor it could communicate with other machines.

2 Answers 2

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It seems that system had the old config in the place.

The symlink /etc/resolv.conf pointed to ../run/resolvconf/resolv.conf

Changing it to point to /run/systemd/resolve/resolv.conf which is managed by systemd.

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  • What was the issue actually? Without changing symlink, it works after restart.
    – Abishek
    Commented Dec 26, 2019 at 9:31
  • How come VM was not accessible via SSH
    – Abishek
    Commented Dec 26, 2019 at 9:32
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    This warning is logged by systemd-resolved, whenever a name can not be resolved by the DNS system (e.g. nslookup www.domain.com). This can be tolerated and is no reason to be alarmed. Commented Dec 26, 2019 at 9:35
  • Actually it's a issue for us. Communication is stopped completely.
    – Abishek
    Commented Dec 26, 2019 at 9:46
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I'm dealing with a similar issue (server inaccessible, even by ssh). In my case, the NXDOMAIN log looks to be a red herring.

I/O utilization spikes massively before an outage, similar to https://serverfault.com/a/933194/523972: enter image description here

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