RE: [cobalt-users] Apache DNS lookups

["Andy Brown" <andy.brown@xxxxxxxxxxxxx>]

> Hi All,
> 
> I'm running webalizer with DNS lookups on the web.log files. 
> The DNS lookups take a long time (on average 150 
> address/min). What implications would it have to switch on 
> DNS lookups for Apache? 
> IMO this would spread the load of doing the lookups or am I wrong?
> 
> Thanks,
> Edwin


Hi Edwin,
I would recommend leaving your logs DNS work to be handled by Webalizer.
The reason is because webalizer is an off-line package, i.e. it doesn't
actually push data directly to site visitors, it simply runs, does its
work and writes out html that can be viewed later.

Therefore it doesn't impact upon when people actually look at their log
files/web sites. However, turning dns lookups ON in Apache DOES cause a
slow-down, because apache has to deal with the DNS lookup, wait for the
reply then log it. This can cause connections to view any web-page to
slow down which is definitely undesirable.

As you mentioned spreading the work-load, it wouldn't achieve this as it
would concentrate the load onto Apache, then webalizer would have an
easy life since it wouldn't have to do any DNS look-ups.

One minor thing you could check, and that is what DNS server you're
using in the /etc/resolv.conf and see if you can find one closer/faster
to use if you think the DNS is a problem, although the timings you say
seem pretty speedy to me.

Regards,
andy@xxxxxxxxxxxxxxxxxxxxx
http://ineedlinux.info/