Lab 9-1 Remove DNS Dependencies from CUCM


By default, a CUCM server refers to key servers, including itself, by name rather than by IP address. This works, but makes your phone system vulnerable to DNS outages. Best practice is to reconfigure CUCM with explicit IP addresses so that your phone system will continue to operate even when the phones are unable to reach their DNS servers.


Starting Point

You should already have a working CUCM install within a virtual machine with a supporting network and services, as described in lab A-1. This is the same setup you used in Lab 8-1. If CUCM and your web browser aren't already running, start them. Detailed instructions are contained in the first several steps of 8-1.

Table 1. Important Addresses and Logins
CUCM AddressCUCM Admin Login / PasswordCUCM OS Admin Login / Password / ciscoclass
(Used for almost everything)
cucmroot / ciscoclass
(Used for the OS Admin interface and the console login)


What menu sequence takes you to the screen where you can change how the CUCM server refers to itself, from a name to an IP Address?

What menu sequence takes you to the screen where you can change how the CUCM server tells phones to refer to it, from a name to an IP address?

Exam Objectives

This is never explicitly mentioned in Cisco's exam objectives, but understanding the inherent weakness introduced by CUCM's default dependence on DNS may help you diagnose end user problems, as requested in the exam objectives in the table below.

Table 2. Exam Objectives
5Provide End User Support
5.2Define fault domains using information gathered from end user
5.3Troubleshoot endpoint issues

Lab Walkthrough (Screenshots are clickable)

In your web browser, navigate to the Cisco Unifired CM Administration page ( and log in (student/ciscoclass). Under the "System" menu, choose "Server." If the list of servers is empty, hit the [find] button to show the complete list of servers (you only have one).