There are some situations in which configuring and using DNS might be unavoidable. For example, if Network Address Translation (NAT) is required for communications between the IP phones and Unified CM in the IP Communications network, DNS is required to ensure proper mapping of NAT translated addresses to network host devices. Likewise, some IP telephony disaster recovery network configurations rely on DNS to ensure proper failover of the network during failure scenarios by mapping hostnames to secondary backup site IP addresses.
If either of these two situations exists and DNS must be configured, you must deploy DNS servers in a geographically redundant fashion so that a single DNS server failure will not prevent network communications between IP telephony devices. By providing DNS server redundancy in the event of a single DNS server failure, you ensure that devices relying on DNS to communicate on the network can still receive hostname-to-IP-address mappings from a backup or secondary DNS server.
Note Hostname resolution within the cluster via either the local HOSTS file or DNS queries is performed only at subsystem initialization (that is, when a server is booted up). As a result, in order for a server within the cluster to resolve a DNS name that has been changed in either the HOSTS file or the DNS server, the Cisco CallManager Service must be restarted on all servers within the cluster.
â¢Resolve fully qualified domain names to IP addresses for trunk destinations
â¢Resolve fully qualified domain names to IP addresses for SIP route patterns based on domain name
â¢Resolve service (SRV) records to host names and then to IP addresses for SIP trunk destinations
When DNS is used, Cisco recommends defining each Unified CM cluster as a member of a valid sub-domain within the larger organizational DNS domain, defining the DNS domain on each Cisco MCS server, and defining the primary and secondary DNS server addresses on each MCS server.
SIP traces provide key information in troubleshooting SIP Trunks, SIP
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Please find the attached HTML document, download and open it on your PC.
This provides an easy to use form where you simply answer a few
questions and it will render the proper jabber-config.xml file for you
to copy/paste. There is built in logic to verif...
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