This documents describes the recommended way to install Domain Name System (DNS) as well as some Cisco CallManager release 3.0(1) known caveats related to DNS configuration. It also describes the commands needed to change the DNS server and domain name in Cisco Unified Communications Manager 7.0.
There are no specific requirements for this document.
The information in this document is based on Cisco CallManager 3.0(1) and Cisco Unified Communications Manager 7.0.2
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Refer to Cisco Technical Tips Conventions for more information on document conventions.
DNS is required for a successful installation of Cisco CallManager because of Structured Query Language's (SQL) dependency on DNS during the install process. However, after installation is complete, Cisco CallManager can run without DNS as long as specific criteria are met. Also, when you run with DNS, use caution to ensure that all known caveats are circumvented.
This is a list of known DNS problems with Cisco CallManager 3.0(1):
If you want to use DNS, this is the recommended way to install it:
Configure the DNS server in the TCP/IP Properties Control Panel:
Click the Advanced button, and then click the DNS tab. Make sure the DNS server you entered appears under the DNS server addresses, in order of use field. Make sure the Append primary and connection specific DNS suffixes and the Append parent suffixes of the primary DNS suffix options are checked. Define the DNS suffix for this machine in the DNS suffix for this connection box. Finally, uncheck the Register this connection's addresses in DNS box.
Right-click on My Computer on your desktop, and then select Properties. This dialog box appears:
Click the Properties button. In this box your "Computer name" must match what is configured in DNS as the hostname for this machine.
Click the More button. In the dialog, make sure the Primary DNS suffix of this computer field is blank and the Change primary DNS suffix when domain membership changes box is unchecked.
If any changes are made to the computer name or the dialog, the computer must be restarted. You are prompted to restart after you answer OK to all the dialogs.
For the Cisco CallManager in question, ensure that the DNS server that contains the hostname contains both a host entry and a PTR record for the reverse-DNS entry.
Note: Without this reverse DNS entry, Cisco CallManager clustering does not work.
If DNS is not used, then ensure that all of the DNS configuration dialog boxes are empty so that the server does not have any DNS servers configured at all. If the server does contain DNS servers, and if IP addresses are used as Cisco CallManager names, the server still relies on reverse-DNS.
From the Cisco CallManager Administration web page, complete these steps in order to configure Cisco CallManager:
Go to the System > Server menu.
Click on each of the servers and make sure they are either configured as DNS hostnames (not fully qualified domain names) or IP addresses. In this example, DNS hostnames are used.
A DNS server represents a device that resolves a hostname into an IP address or an IP address into a hostname. If you have a DNS server, Cisco recommends that you enter Yes to enable DNS at the time of installlation. Disabling DNS limits the system ability to resolve some domain names.In order to change the DNS server name and domain name follow the below mentioned commands:-
set network dns primary <your primary dns IP address>
set network dns secondary <your secondary dns IP address>
set network domain <node.company.com>
Note: It is advised to take the backup of the servers before performing these steps and then reboot the cluster after changing the hostname.
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Refer to Cisco Technical Tips Conventions for information on conventions used in this document.