Impact in change the DNS's Ip Address on the Cisco UC 14 and UCCX 12.5

[csrlima]

Hi team, i know how to change the dns of CUCM 14 and UCCX 12.5 ( set network dns .... ) but i dont know in this version if i need to reboot servers (CUCM is a cluster of 3) and uccx is standalone)  and the correct order to do it. i dont find similar documents 

This company is changing DNS IP Addresses (AD servers) and i need to avoid problems with Collaboration Services, so:

i have to change CUCM dns

i have to change UCCX dns

i have to change Expressways DNS

I have to Change LDAP server in CUCM

i have to change ip helper address in voice phones vlans ( because DHCP server is changing with AD) and also have to change DNS servers in DHCP Voice Pools.

Am i missing something?

Best Regards

[b.winter · Accepted solution]

No, you don't need to reboot anything of your list.
And no, there is no "correct order". Just do it.

For the phones, you should probably decrease the lease time, before you change it. Because even if you have changed the DNS server in the DHCP pool settings, the phones will still have the old IP. And it can take days, until the request a new IP (with the new DHCP-settings).

And probably you need to do it in a maintenance window, because you cannot change the DNS servers at the same time and therefore, in the second where to DNS server IP changes, anything of your list will still point to the old IP and will not be able to resolve or provide DHCP.

[aalejo]

Hey Sr,

I saw this response but on CUCM documents state that changing CUCM DNS does need  server reboot. (it is on every CUCM admin notes since CUCM 12)
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/14SU2/adminGd/cucm_b_administration-guide-14su2/cucm_b_test-adminguide_chapter_011110.html?bookSearch=true

From that document:
Note "If you change the IP address for the DNS servers, you must reboot the server through the utils system restart CLI command."

Any ideas?

Thanks

Alex

[Nithin Eluvathingal]

Although the admin guide mentions that a server restart is required, changing the DNS IP works without a restart based on our experience with CUCM.

If you experience any issues in resolving the hostname post changing the DNS IP, you might need to consider this step. It requires a maintenance window

[Nithin Eluvathingal]

You don't need to restart the servers if its just DNS ip address.

Dont you have IMP, unity gateway etc where also we configure DNS ?

As @b.winter mentioned do this on maintenance Window. And for the phones to take the new DNS IP reducing lease time will be a good option.

2.12.0.0

[csrlima]

I dont have to worry about certificates also?

I dont have to worry about UCCx licenses also?

About DHCP and ip phones, as far i have the 2 DNS servers running in parallel for a while, best is do it as soon as possible.

Thanks for your advices and suggestions

[Nithin Eluvathingal]

Certificates will not be affected by the DNS change.

I hope for UCCX you are using smart licensing. And there wont be any impact. Even if there is an issues reregsier will solve the issue.

2.12.0.0

[Roger Kallberg]

In what way would a change of DNS server IP(s) affect certificates?

[Scott Leport]

Hi there,

I think that the certificates would only be a concern if you were changing the domain name. From your original post you don't mention it, so I guess that's not required?