[nsd-users] NSD not starting

[Michael A. Peters]

First from /var/log/messages -

Feb 13 13:22:29 li354-217 systemd: Cannot add dependency job for unit 
microcode.service, ignoring: Unit is not loaded properly: Invalid argument.
Feb 13 13:22:29 li354-217 systemd: Started NSD DNS Server.
Feb 13 13:22:29 li354-217 systemd: Starting NSD DNS Server...
Feb 13 13:22:29 li354-217 nsd[30882]: nsd starting (NSD 4.1.14)
Feb 13 13:22:29 li354-217 nsd: [2017-02-13 13:22:29.498] nsd[30882]: 
notice: nsd starting (NSD 4.1.14)
Feb 13 13:22:29 li354-217 nsd[30882]: can't bind udp socket: Cannot 
assign requested address
Feb 13 13:22:29 li354-217 nsd: [2017-02-13 13:22:29.500] nsd[30882]: 
error: can't bind udp socket: Cannot assign requested address
Feb 13 13:22:29 li354-217 nsd[30882]: server initialization failed, nsd 
could not be started
Feb 13 13:22:29 li354-217 nsd: [2017-02-13 13:22:29.518] nsd[30882]: 
error: server initialization failed, nsd could not be started
Feb 13 13:22:29 li354-217 systemd: nsd.service: main process exited, 
code=exited, status=1/FAILURE
Feb 13 13:22:29 li354-217 systemd: Unit nsd.service entered failed state.
Feb 13 13:22:29 li354-217 systemd: nsd.service failed.

I assume the microcode.service is an unrelated CentOS 7 bug, based on 
google searches, seems to be harmless noise caused by a bad regex and 
doesn't cause services to fail. The rest though is NSD not starting.

NSD 4.1.14

The host is a Linode VM that was running just fine for a long time. All 
the host does is NSD. Another just like it still running fine.

This host that is not starting, a few days ago Linode migrated the VM to 
a different machine and I suspect that is the cause.

It's not firewall, I turned it off and tried just to make sure.

It's not anything else using port 53 - no bind or unbound, and an nmap 
of the host shoes port 53 closed, not listening or blocked.

I suspect something to do with how the image was migrated resulted in 
port 53 no longer working. My ssh still works (only other service 
listening) but I use a custom high port above 1024 for that.

linode uses KVM - I really only have experiences as a client running an 
image, not in the KVM side of things itself.

Anyone know what might be possibly NSD on an image that ran well for 
over a year to suddenly no longer be able to bind to port 53? The two 
suggestions I got from linode support staff I had already checked and 
weren't the issue (first suggested I had started bind, second suggested 
my firewall was the issue, I verified both were not the cause BEFORE I 
filed a ticket) so I think they are clueless.

Same setup on another host that wasn't migrated is still working peachy.

This is my third nameserver, so with this not running I only have two 
and I do not like to only have two.

It's a slave, not a master.

Thank you for any suggestions.