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If DNS is not enabled during CUCM installation it can't be used later?

Hi all,

seems to me this can't be true but when attended one telepresence class they told me the following:

"It is recommended to install CUCM with DNS enabled even if it will not be used initially. If you do not select the DNS option during installation, you would have to reinstall CUCM to enable it later."

Any comments are appreciated.

6 REPLIES
Super Bronze

If DNS is not enabled during CUCM installation it can't be used

Hi

No - that's not true at all. You can configure DNS by applying commands on the server CLI:

set network dns primary 2.2.2.2

set network dns secondary 1.1.1.1

set network domain domain.com

Regards

Aaron Harrison

Principal Engineer at Logicalis UK

Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
Hall of Fame Super Silver

If DNS is not enabled during CUCM installation it can't be used

This used to be the case when Appliance CUCM was version released (version 5.0), but this was enhanced in either version 6.X or 7.X, so if you are on any recent version you will not encounter the issue and simply follow Aaron's guidlines on how to add it.

HTH,

Chris

New Member

Re: If DNS is not enabled during CUCM installation it can't be u

Aaron / Chris

I am hoping you guys have done this before and can provde some feedback.  I currently do not have the domain name configured for my CUCM 7.1 cluster.  Performing a show network eth0 shows:

DNS

Domain       : Not configured  <-- Not set

Gateway      : 10.48.116.1 on Ethernet 0

After a recent upgrade to my companys exchange servers from 2003 to 2010 I noticed I stopped getting RTMT alerts.  I took a packet trace from the CUCM publisher and saw in the trace I was getting invalid user ID.  THe trace showed the alert from field was RTMT instead of RTMT@company.com.  I guess this worked in the 2003 exchange becasue the relay agent only looked at the IP address I was coming from.  2010 requires a domain name.

I found this article and according to the requirements to configure alerts to be sent via e-mail, the Domain name should be configured to properly addressed this request to the SMTP server:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/service/7_1_2/rtmt/rtconfal.html

Here is were I get nerviouse. When I type the command set network domain company.com I get the WARNING:

Adding/deleting or changing domain name on this server will break database replication. Once you have completed domain modification on all systems that you intend to modify, please reboot all the servers in the cluster. This will ensure that replication keeps working correctly. After the servers have rebooted, please confirm that there are no issues reported on the Cisco Unified Reporting report for Database Replication.

The server will now be rebooted. Do you wish to continue.

So I interpert this as telling me I will have to perform the set network domain command on all 8 of my subscribers and then reboot them?

IF you guys have done this did you have to perform a drop replication and then rebuild the replication?  If you have not done this do you know if you have to.  Since I have Contact Center Enterprise and Express in my CUCM cluster and we are 24x7 I have to be cautious.  When I have had to rebuild replication before it has taken and hour and it was not a good time.

Thanks in advance for any feedback you may be able to provide!

Super Bronze

Re: If DNS is not enabled during CUCM installation it can't be u

Hi

Firstly, have you gone in to RTMT and edited the sender address? AFAIK it's based on the config applied in that tool not the domain of the server.

Re: setting the DNS domain - you can do it, if you are on VMware it will change your license MAC and you'll have to rehost your licenses. If you're on hardware it won't be an issue.

The other thing that affects 8.x is if you go on a big changing-the-DNS domain bender on the whole cluster you might end up with cert/security-by-default issues. Again, you're on 7 so it shouldn't be a problem.

If you do it one server at a time you should be fine. You can get problems with replication afterwards so you might have to reinitialise replication - take a DRF first in case.

Aaron

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
New Member

Re: If DNS is not enabled during CUCM installation it can't be u

Hi Aaron,

Unfortunatly in the RTMT version 8.1 for CUCM 7.1.5 the option to set the sender address is not present   I did see the sender address in RTMT version 8.91 for my CUCM 8.6 clusters.

Thanks for the feedback Arron!

Del

Hi Aaron,

Hi Aaron,

As you said, the DNS servers can added after the installation, so could you modify the DNS servers if IT staff changes them in the future?

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