Enable DNS on CUCM

[Difan Zhao]

Our company rolls out a policy to not maintain an internal NTP server anymore. Instead, it is asked to use "ca.pool.ntp.org". In this case, I will need to enable DNS lookup on the CUCM server. Is there any concern about it? All the configs such as SIP trunk or gateways are all configured with IP address. Thanks.

Just want to make myself more clear. Once DNS is enabled, does it do a reverse DNS lookup on all the IPs configured? Does it do lookup on the CUCM's name? Will any of these slow the system down? Thanks

[Jonathan Schulenberg]

Trunks, CallManager Group nodes, Enterprise Parameters, Phone Service URLs, etc that you have configured with an IPv4 address will continue to function as-is with DNS enabled. The CUCM cluster must have forward and reverse lookup of all cluster members working perfectly though.

Also, be careful with NTP Stratums: CUCM-IM&P considers itself unsupported if it is stratum five or beyond. Don’t forget that subscribers obtain time from the publisher.

Lastly, don’t forget that NTP is a critical supporting service; unreliable time can/will cause problems, especially with database replication.

[HARIS_HUSSAIN]

1) This should not be an issue. Make sure to configure both Forward and Reverse DNS Entries for all IPT Server.
2) Also make sure to sych CUCM to Statum 1 or 2 NTP Source

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Thanks,
Haris