CUCM warning: DNS unreachable

[cukouncukoun]

Hi all,

after upgrade CUCM from 8.6 to 11.0.1.20000-2 we found this warning message that DNS is unreachable on the publisher CUCM GUI.

When I tried to resolve some hostnames from both CUCM nodes through CLI it was normally worked so DNS is not unreachable.

Any ideas?

Thanks

Tomas

[Mohammed al Baqari]

Hi,

Can you check how many DNS servers are configure on CUCM? Could be one of them isn't reachable.

[cukouncukoun]

I have 2 DNS servers and both are working from the both CUCM nodes - checked through CLI (utils network host hostname server 1rd server + 2nd server).

This warning message is displayed just on the pub. Everything is seems to be OK - sync, all services..

Tom

[Mohammed al Baqari]

Hi,

I am not sure what domain names you are trying to resolve but can you try google.com as below on both servers

utils network host google.com

[cukouncukoun]

I tried www.google.com from both nodes through both DNS servers and its working as expected.

I will try to reboot whole cluster tomorow so maybe it will help me

T

[Rolando Valenzuela]

Cool, keep us updated.

Rolando Valenzuela.
 

[cukouncukoun]

I resolved it..:-)

Issue was caused by first DNS server beucase I found that someone created second A record for the publisher IP so I delete this second record and create a alias for it.

So message 'DNS unreachable' does not mean that DNS server is really unreachable but that DNS server returned for CUCM pub IP address 2 reverse records.

Tom

[Jitender Bhandari]

Hi Tom,

A quick way to identify that is to run "Utils diagnose test" it check for both forward and Reverse DNS and is a better then just pinging the server as it could also be a possible issue with DNS record like in your case.

HTH

JB

[Rolando Valenzuela]

You can also check this guide :)

http://amyengineer.com/2015/09/09/updating-dns-server-ip-addresses-on-cisco-voice-servers/

[Alex Andruszkiw]

I had the same issue, "WARNING: DNS unreachable" after upgrading Unity to 10.5.2.13900-12.  I inspected forward and reverse DNS entries on our DNS servers and found 2 reverse DNS entries for this host, removed the outdated one, re-ran the CLI command utils diagnose test then the DNS warning message cleared.

[Rolando Valenzuela]

Did you get the message right after the upgrade? Did you try to reboot the PUB?

Have you noticed any problem with the system beside the warning?

Check also if the sync is working.

Regards.

Rolando Valenzuela

[feihua]

Hi,

Did you get any updates for this issue?

I also have the same issue here. I upgraded cucm from 10.5 to 11.0, it shows warning: DNS unreachable.

but I can ping dns servers from cli and also hostname can be resolved. also the service hasn't been affected.

Anyone can help to check this issue?

Thanks a lot,

Holly

[Rolando Valenzuela]

Hi Holy, check Tom's last comment

I resolved it..:-)

Issue was caused by first DNS server beucase I found that someone created second A record for the publisher IP so I delete this second record and create a alias for it.

So message 'DNS unreachable' does not mean that DNS server is really unreachable but that DNS server returned for CUCM pub IP address 2 reverse records.

Tom

Rolando Valenzuela.

[feihua]

Thanks for your reply.

yeah,I already checked that updates. And I also check that records on my DNS server. it works fine. only one A record for cucm.

Still have this issue.

Can you please give some advises ?

Thanks a lot,

Holly

[Rolando Valenzuela]

If nothing is broken I should not panic, maybe is just a glitch, have you try a rebooting the server?

Rolando Valenzuela.