Per-machine decentralised DNS caching - nscd/lwresd/etc

Posted by Dan Carley on Server Fault See other posts from Server Fault or by Dan Carley
Published on 2010-01-26T17:32:30Z Indexed on 2010/03/09 5:08 UTC
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Filed under:

dns

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cache

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Performance

Preface:

We have caching resolvers at each of our geographic network locations. These are clustered for resiliency and their locality reduces the latency of internal requests generated by our servers.

This works well. Except that a vast quantity of the requests seen over the wire are lookups for the same records, generated by applications which don't perform any DNS caching of their own.

Questions:

Is there a significant benefit to running lightweight caching daemons on the individual servers in order to reduce repeated requests from hitting the network?
Does anyone have experience of using [u]nscd, lwresd or dnscache to do such a thing? Are there any other packages worth looking at?
Any caveats to beware of? Besides the obvious, caching and negative caching stale results.

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