topic Re: WARNING: DNS unreachable in Unified Communications Infrastructure

WARNING: DNS unreachable

Muhammadnawaz — Wed, 19 Oct 2022 05:46:31 GMT

Hi everyone,

We have an issue since the activation of license on primary CUCM, initially the secondary CUCM was coming up with this warning message as mentioned in the title and below. now this warning message appears on both Primary/Secondary CUCMs. please suggest the solution to fix this issue as we have tried to restart the CUCMs also reinstall the license but still the issue is same.

Primary:

Secondry:

Thanks in advance for support.

Re: WARNING: DNS unreachable

Muhammadnawaz — Wed, 19 Oct 2022 06:20:04 GMT

Also please comment about this issue we got on the CUCM, even both CUCMs are in cluster but still it is showing the warning message like this (WARNING: No backup device is configured. This is required to recover your system in case of failure).

thanks for experts opinion.

Re: WARNING: DNS unreachable

Nithin Eluvathingal — Wed, 19 Oct 2022 06:39:10 GMT

Check both forward and reverse lookup if its working.. it could be because of the Reverse lookup. I have seen this most commonly when reverse lookup fails.

issues the below command from CUCM CLI

utils diagnose test

Re: WARNING: DNS unreachable

Nithin Eluvathingal — Wed, 19 Oct 2022 06:39:38 GMT

Add a backup device and take backup.

Re: WARNING: DNS unreachable

Dmytro Benda — Wed, 19 Oct 2022 06:39:47 GMT

Hello,

BACKUP Warning - to remove it, you have to configure Cisco DRS. It is a connection to SFTP server for your CUCM back up.

Here is a guide how to configure DRS:CUCM DRS configuration guide

As for your DNS issue - can you ping your primary DNS server from your Publisher CUCM CLI?

My Cisco Unified Communications Blog

Re: WARNING: DNS unreachable

Muhammadnawaz — Wed, 19 Oct 2022 07:46:36 GMT

Hi Dmytro,

thanks for the comments, yes am able to ping primary DNS server from the publisher.

Re: WARNING: DNS unreachable

Dmytro Benda — Wed, 19 Oct 2022 08:16:56 GMT

Hi @Muhammadnawaz

Ok, please read this post too:

https://community.cisco.com/t5/ip-telephony-and-phones/cucm-warning-dns-unreachable/td-p/2714928

Isn't it your case?

My Cisco Unified Communications Blog

Re: WARNING: DNS unreachable

Nithin Eluvathingal — Wed, 19 Oct 2022 08:57:35 GMT

Am you check the forward and reverse lookup for the cucm nodes ?

Re: WARNING: DNS unreachable

Muhammadnawaz — Wed, 19 Oct 2022 09:21:45 GMT

Hi Nithin,

thanks for the help, I check the diagnostic on both CUCMs Reverse Lookup is failed and output is as follows..

Re: WARNING: DNS unreachable

Nithin Eluvathingal — Wed, 19 Oct 2022 09:29:53 GMT

Add reverse entry/ PTR RECORD on your dns and that solve the issue