Aastra 9000i Series Administrator's Manual page 677

Configuring "DNS Host" Pre-caching
3 Save the file as "<filename>.txt". For example, "hostfile.txt".
4 Using a text-based editing application, open the aastra.cfg file for the phone(s) for which you want to
apply the DNS hostfile.
5 Enter the following parameter in the aastra.cfg file followed by the host file name as the value:
sip dns host file: <filename>.txt
For example:
sip dns host file: hostfile.txt
Note: If using a text file on a PC to enter this value, you must enter a carriage return (CR) after
entering the host file name.
6 Save the file. Make sure the aastra.cfg and the hostfile.txt files are on the configuration server in your
network before downloading to the phone(s).
7 Restart the phone(s) in your network.
The phone(s) downloads the specified host text file and stores it locally on the phone's flash memory.
Upon each subsequent boot of the phones, if the host text file is available on the configuration server,
it is downloaded to replace the locally cached copy; otherwise, the previously cached copy is
retained and used unchanged.
The configuration of the phone(s) can now use server1, server2, or server3 for SIP or other services
instead of using the IP addresses. The phones will continue resolving the host names even if DNS on
the network has conflicting or missing entries for server1, server2, or server3, or if the local LAN DNS
server fails to respond.
Configuring DNS "Service (SRV) Records" pre-caching
In addition to using a host file to resolve host names to IP addresses, an Administrator can also
configure DNS "SRV records" (Service Records) for geographic redundancy and failover
between application servers in the network.
The SIP registration and SIP proxy features on the phones previously allowed the use of server
queries only to live DNS servers. Using the host file and specific DNS SVR parameters extends
this mechanism to allow pre-configuration of server values in the
aastra.cfg file. The following new parameters are used for this feature:
• sip dns srvX name
• sip dns srvX priority
• sip dns srvX weight (supported in a future release)
• sip dns srvX port
• sip dns srvX target
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