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

[Jitender Bhandari]

Hi Michael,

i would says to run "Utils diagnose test" and if it fails on revers DNS then check your DNS server.

JB

[Deepak Rawat]

Your understanding is correct  Michael that starting 11.x there are some rigorous checked added for DNS resolution and the warning cum error message you are able to see on Publisher GUI page is part of that only. As suggested by Jitender do a utils diagnose test and look for any issues there with your forward and reverse lookup entries.

Regards 

Deepak

[michael mack]

This really should be a bug. Its not a rigorous test if it fails on a valid DNS configuration. I was pretty disappointed that Cisco is treating this like its a valid check on DNS. Its clearly not correct.  I'm hoping they fix this.  Heck, just having the PLM run on the CUCM box means you cannot use DNS, as you'd have one name for the PLM server and a different one for the CUCM, which you can't do because of this.  

[michael mack]

So the new checks that the CUCM performs is actually invalid.  If you have any entry that points to the CUCM's IP address with a different name, this error pops up, even though its a 100% valid DNS configuration.  

In my case, I was using the pre-configured image from Cisco, including the pre-configured router.  The router has entries for both the CUCM and the PLM, which are of course the same IP address.  This caused the CUCM to state that it could not communicate with the DNS server.  Even though this is a completely valid DNS configuration (straight from Cisco) you have to remove the extra entry.