Monday, September 7, 2015

The growing importance of DNS in your CUCM configs

Hi Guys!

It used to be that DNS was an afterthought for most CUCM deployments, many engineers advocated at one point or another just using an IP address rather than dealing with the system team who could either be extremely cooperative or extremely slow.

Those days are GONE, my friends. 

Every bit of UC software you use should be properly configured with DNS.

 Infact, anywhere you CAN use DNS, you should be using it.

The main driver for this is definitely Jabber, I can't count the number of things that can go wrong with Jabber if you do not have your DNS configured correctly.

If you absolutely must get a system up very rapidly and the sysadmin team have been very slow to get there side finished, you can use a router as a temporary DNS server:

The config for this is shown below:

conf t
 ip domain-name
ip  dns server
ip name-server 8.8.8.8 4.4.2.2

ip host _cisco-uds._tcp.ccierants.com srv 0 10 8443 cucm01.ccierants.com
ip host cucm01 192.168.1.10
ip host unity 192.168.1.20

ip host imp 192.168.1.30
ip host _cuplogin._tcp.ccierants.com srv 0 10 8443 imp.ccierants.com



As you can see from the example above, you can use the host command to specify manual DNS entries, you can even do SRV records etc, the only records i can't seem to see are CNAME records, but for our purposes this does not matter.

You can then point your UC servers to this router as there DNS server as a temporary workaround while you wait for the system administration team.