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From Brian Dessent <>
Subject Re: [users@httpd] HostnameLookups
Date Wed, 11 Feb 2004 17:39:16 GMT
"j.travis" wrote:
> I have read that it is a performance liability to have HostnameLookups
> turned on.  What I am wondering is will Apache2 do a
> HostnameLookup -before- it responds to a request? (in which case that
> could indeed be a very big liability) or does it do it independently of
> requests (but just sometime before it gets logged). If this is the case
> it seems like it would be only a slight overall use of bandwidth and a
> very miniscule performance hit.  It certainly makes the log files more
> interesting to browse through...

If you were using 1.3 you could try mod_dns:
<>  This module supposedly improves
the DNS performance significantly through caching, so that it's feasible
to turn on HostNameLookups again.

But, that aside, there's nothing that says you can't process the logs
offline.  Apache comes with 'logresolve', and there are a number of
other similar and more feature-rich alternatives (adns, bulkdns, etc.)
that are all specifically to do fast reverse DNS lookups with caching,
for log processing.  You can filter your live logs through one of these
programs, and use the output for whatever you want.  Or you can wait
until you rotate the logs and then replace them with the resolved


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