change host name from IP address to FQDN on Cisco UCM

[karen.johnson5801]

folks,

what is the repercussion of changing the "Host name" under "Server Information " on UCM from ip address to FQDN ?

We only have Unity and UCCX , and EM running on cluster.

Tks,

K

[Deepak Rawat · Accepted solution]

Karen, there are no issues at all whatsoever in changing the server information from IP Address to FQDN. Just make sure that you have defined the Reverse and Forward look up entries on your DNS server for this before making the change.Simply use the below commands from CUCM, UCCX, UCxN CLI just to ensure that DNS resolution is working fine back and forth between the servers:

utils network host <IP Address of Target server>

utils network host <FQDN of Target server>

It is usually recommended that this change should be followed by server reboot to update the necessary entries in all the system files. Check below thread wherein customers had done this and faced no issues at all:

https://supportforums.cisco.com/discussion/12495331/change-server-name-ip-fqdn

Regards

Deepak

[karen.johnson5801]

Thanks Deepak,

what exact command to use " Reverse and Forward look up entries on your DNS " ?

Down the road, we don't need to worry when phone or MGCP gateway reboot will not find the ip address?

so do we need to reboot server as well?

K

[Deepak Rawat · Accepted solution]

utils network host <IP Address of Target server>

utils network host <FQDN of Target server>

So the way you will use is like this, run the above commands from the CLI of UCCX, UCxN servers (any UC servers CM will be interacting with) to make sure they are resolving fine. IP Address and FQDN of target server in this case will be the CUCM since you are changing the server information for that. You can run the above commands from all the CM servers in the cluster as well to make sure it works fine for CM as well.

Down the road, we don't need to worry when phone or MGCP gateway reboot will not find the ip address?

Nothing will happen Karen as mentioned in my previous thread, the bottom line is that your DNS should be working fine and that's it. Rebooting the servers should be done.

Regards

Deepak

[karen.johnson5801]

Thanks.

[karen.johnson5801]

hi Deepak,

so we run the "utils network host"  after the change, right?

this is what I got when do above command from UCCX , is this ok "Nothing found"  or we just worry on "External Resolution" ?

admin:utils network host 172.22.20.25
Local Resolution:
Nothing found

External Resolution:
35.20.22.172.in-addr.arpa domain name pointer s01-uc-ucm-p.jazzy.com.

K

[Deepak Rawat]

Karen without any doubt this is not an issue at all. Reason for this is that UCCX , CM etc from where you are issuing this command is not a DNS server but only a DNS client hence no local resolution is possible. It is actually the DNS server that is doing the job hence everything will be under External Resolution. Below is the output from my UCCX server as well. 

admin:utils network host 10.146.138.3
Local Resolution:
Nothing found

External Resolution:
3.138.146.10.in-addr.arpa domain name pointer cucm10pub.ccx.cisco.com.
admin:

One thing I noticed in your output there is that 172.22.20.25 is resolving to 35.20.22.172 instead of 25.20.22.172. So you might need to check your Forward (A) Record and Reverse (PTR) Record for this on the DNS server

Regards

Deepak

[karen.johnson5801]

hi Deepak,

I just tried update the ip address to be FQDN under "System->Server" to pub01.jazzy.com

(I don't change ip address , just updated it with FQDN)

And the phones and gateway are down for 60 seconds before register back to "pub01.jazzy.com"

is that expected and I don't need to worry or change anything on UCCX and Unity?

K