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From "Robert Andersson" <>
Subject Re: [users@httpd] logresolve is not doing it job
Date Thu, 21 Aug 2003 04:26:58 GMT
Farid Hamjavar wrote
> Bad host: !=
> that's bogus because that IP# is dns resolvable.
> How come logresolve is unable to resolve it?

Because it does a 'double reverse DNS lookup', that is, it first do a
reverse lookup on the IP to get a hostname and then lookup that hostname to
compare the original IP with. If they don't match, it is deemed 'bogus'.

In this case it is obvious that the visitor was a dial-up user, or other
DHCP client, for which a hostname is more or less randomly generated when
the client is assigned an IP. When you process your logs, the user is long
gone and/or has a new IP and hostname, and the previous are given to others
and don't match anymore.

Robert Andersson

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