Re: [squid-users] dns-related cache problem (squid 3.3.8)

From: Alex Rousskov <>
Date: Wed, 09 Oct 2013 11:50:43 -0600

On 10/09/2013 06:00 AM, Dash Four wrote:

> I then stopped (-k shutdown)
> and then started squid without touching the existing cache - again,
> squid was still referring to the old host->ip mapping.

For HTTP misses, the above is not possible (as Amos said) because Squid
does not store its DNS caches on disk.

For HTTP hits, the above is possible and is the correct behavior because
HTTP cache is indexed by the domain name (and more), not by the IP
address(es) that domain name resolves to.

Are you talking about HTTP hits or misses?

> Yes, inotify is fully supported, but my issue is with squid caching dns
> requests - that should not happen, or, at the very least, I should be
> able to disable this behaviour.

The latter is correct. A good caching DNS agent should have a
configurable cache.

As for /etc/hosts caching specifically, the situation is exacerbated by
the fact that Squid ignores /etc/hosts expiration (signaled by file
changes). AFAICT, there is no modern standard that covers /etc/hosts,
and RFC 952 either assumed that /etc/hosts is only used for DNS
bootstrapping or just did not bother to cover mapping expiration, but it
is reasonable to assume that changing /etc/hosts [timestamp] should
trigger invalidation of the cached information (and a reload).


Received on Wed Oct 09 2013 - 17:51:20 MDT

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