IP phones DNS problem

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Nov 8th, 2007
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Hi all

i have two callmanagers, publisher and subscriber and everything works fine except failover to the subscriber once the publisher goes offline. If i shutdown the callmanager service in the subscriber, IP communicators re-registers with the subcriber but all the other phones dont. I am thinking it's something to do with DNS. The phones shows the callmanager names (not IP addresses) in their configuration and they can't resolve the subsriber name to IP. I have configured the callmanagers names in DNS server but no success. i can ping the names from my laptop and everything else a DNS should do works well from a PC. I had to change the services URLs to publisher IP address instead of names because of the same problem. Do cisco IP phones knows how to query a DNS or they just take the IP address of the DNS server and don't know what to do with it? or is it a bug on CCM 5.1.3?



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bwilmoth Wed, 11/14/2007 - 14:13
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Go to system->server on the callmanager and change the name to an IP address, then go to system->control center and stop/start the TFTP service. Reboot the phone and it should work fine

solomonthuo Wed, 11/14/2007 - 22:32
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I have been able to resolve the problem using a different method. I had to put the callmanagers domain name in the IP phones DHCP scope.I realized the phones cannot resolve the name if they don't have a domain name in their configuration. for instance if i put my ccm as ccm1.test.gwety.local, the phones gets the name of the ccm as ccm1 and they can't resolve hence they use the tftp server IP address as the ccm. to solve it i just put test.gwety.local as the domain name in the IP phones dhcp scope. I needed to use the names and not the IP such that i can make one name resolve to different IP addresses. if one server fails the IP phone services will still work using the other resolved IP.


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