Re: [Exim] Long lookup time - almost solved now

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Auteur: Peter Radcliffe
Date:  
À: exim-users
Sujet: Re: [Exim] Long lookup time - almost solved now
michael@??? probably said:
> I found that a local, caching only BIND increases overall performance
> a lot. Note that you will not see the difference on smaller systems.
> I put 127.0.0.1 as first nameserver in resolv.conf and our central
> caching nameservers as secondary nameservers. That way I can restart
> the local BIND without interrupting regular operation, e.g. to get
> rid of the cached records, but usually I enjoy very short latencies.


This topic is somewhat religious and somewhat misleading.

There are situations where running a local to the machine nameserver
will help. There are situations when it will actively make things worse.

If you have a shortage of memory or a very busy mailserver the extra
memory usage and extra context switches of a nameserver on the same
machine can impact performance negatively.

Personally I prefer to have the nameserver on a different machine
which is very close network wise (same local subnet).

If a local cache does make things better then I would recommend
forward-first to another local cache, so you get the benifit of the
local cache but the local machine doesn't have to do as much work (and
it benifits from the cache on the other machine).

P.

-- 
pir                  pir@???                    pir@???