[OpenSIPS-Users] [NEW] DNS Caching Support

Vlad Paiu vladpaiu at opensips.org
Mon Feb 13 11:18:15 CET 2012


A new *DNS_CACHE* module has been added to OpenSIPS trunk, and it will 
also be present in the future 1.8 release.

In the current OpenSIPS design, I/O Operations, DNS included, are done 
in a blocking way, with the SIP workers having to wait for the DNS query 
to return, until further processing can be done. Slow DNS servers are 
often a source of performance degradation, and DNS queries that are not 
resolvable have an even larger performance impact.

The new *DNS_CACHE* module implements the Key-Value Interface [1] to 
allow caching of DNS records in a user-chosen back-end ( local cache, 
memcached, etc. ) for the TTL number of seconds returned in the DNS 
response, thus greatly improving the speed of subsequent DNS requests 
for the same domain. Failed queries ( without any records found in DNS ) 
are also cached with a user-chosen duration.

For a full documentation of the module, visit [2] .
Testing and feedback is very much welcomed.

[1] http://www.opensips.org/Resources/DocsTutKvinterface
[2] http://www.opensips.org/html/docs/modules/devel/dns_cache.html


Vlad Paiu
OpenSIPS Developer

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