Re: [squid-users] How can I make squid ignore cached DNS looks up ?

On 12/06/2014 5:05 a.m., Mark jensen wrote:
>
>
> Hello
>
> we all know that access.log file logs the access Info of Squid, something like that:
> 125213512.746 41762 192.168.1.17 ..............
> 125213513.746 47616 192.168.1.18 ..............
>
>
> MY local DNS server has records like this ( in its revers zone (1.168.192.in-addr.arpa)):
>
> $TTL 60 ; 1 minute
> 17 PTR Mark
> 18 PTR Mike
>
> I have managed to make this record in the access.log file (using the option "log_fqdn on" and by changing the log format):
>
> 125213512.746 41762 192.168.1.17 ..............
>
> to be something like that:
>
> 125213512.746 41762 192.168.1.17 Mark ..............
>
> the problem is that the DNS records keep changing ( something like that ):
>
> $TTL 60 ; 1 minute
> 17 PTR Karl
> 18 PTR Mike
>
> and
>
> $TTL 60 ; 1 minute
> 17 PTR Paul
> 18 PTR Mike
>
> and so on ......
>
> but the squid keep resolving the IP as "Mark", so I guess that Squid use the cached look up so what ever "Mark" change in DNS zone it keeps it "Mark"
>
> My questions are:
>
> 1) what is the option who makes Squid cache looks up ?

The "$TTL 60 ; 1 minute" in the DNS server configuration tells Squid and
a other software looking up the DNS that the record delivered is to be
cached for 60 seconds.

> 2) how to stop this option and make Squid keeps ask the DNS and ignore the cache looks up?

Configure DNS correctly to match the update frequency for the zone. If
that is real-time then the zone TTL needs to be close to 0 and you will
need to lower http://www.squid-cache.org/Doc/config/negative_dns_ttl/
appropriately to match the supeer-low TTL.

Note that it is BAD practice to change a zone file entry more often than
*daily*. Reseting PTR records every 1 minute or less will screw up in a
great many systems, Squid is just one.

Amos
Received on Thu Jun 12 2014 - 10:10:49 MDT