Re: [squid-users] more dns problems

From: Henrik Nordstrom <>
Date: Sat, 24 Nov 2001 10:21:49 +0100

On Friday 23 November 2001 13.16, Proescholdt, timo wrote:

> I think itīs internal DNS as i did not change such a setting.
> Can you tell me about the differences between the internal
> and external setting?

In this specific context:

The internal one has access to the DNS TTL information. The external blindly
uses the DNS TTL you set in squid.conf.

> What i noticed playing around with tcpdump und snoop
> ist, that once i start a request from by browser, a
> dns request from squid to server 1 ( which is down ) is
> made, after 4 minutes a second request is send to server 2


Can you try if the Squid-2.5 snapshots behaves better? There has been some
changes in how the DNS timeouts are managed.

> What i notice again and again, is that for 1 (one ) Page,
> depending on the number of ( pictures , html pages and so on)
> on the page between 10 - an 30 dns requests for the record
> are sent from the cache to the nameserver.

The internal DNS will send multiple queries in parallell if it doesn't have a
valid cached DNS entry and there is multiple parallell requests.

> Maybee these two problems belong together?

Maybe, or somehow the TTL's get messed up before reaching Squid (or
misunderstood by Squid).

> A cannot confirm that reverse lookups are made, but even
> if, the secondary nameserver is secondary for the
> 4[0,1] zones as well and can
> answer PTR queries. ( i tested ).

So you have neither of dig or tcpdump?

> maybe it is a solution to install a caching only nameserver,
> hwo handels the reloving transparently for the squid?

Should improve things somewhat.. but the basic problem still needs to be


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Received on Sat Nov 24 2001 - 02:27:57 MST

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