Re: [squid-users] DNS Caching

On Fri, 23 Sep 2005, Matus UHLAR - fantomas wrote:

>> Good question which TTL it uses in such case. From what it looks inthe
>> source it ignores the TTL of the CNAME record and uses the TTL of the A
>> record. Obviously it should use the least of the two... Please file a bug
>> report on this.
>
> I don't think so. Is should use TTL as received, but reasonable maximum and
> minimum values can be used.

The key question here is what is "TTL as received" in

www.example.com ttl=60 IN CNAME server1.example.com
server1.example.com ttl=360000 IN A 172.16.4.54

when the DNS query is www.example.com A.

Squids DNS cache is quite simplistic and does not cache the CNAME
relations, only the A responses of the lookup. As a result today Squid
uses the ttl of the A record which is not entirely correct as this ttl is
for server1.example.com not the queried www.example.com. To conform with
normal DNS caching it should use the least of the two I think.

But I won't touch this without a bug report where to keep a diary of the
change and preleminary patches.

Regards
Henrik
Received on Fri Sep 23 2005 - 15:08:29 MDT