[Pdns-users] wiping the packet cache

Christof Meerwald cmeerw at cmeerw.org
Wed Sep 21 20:18:54 UTC 2011

On Wed, 21 Sep 2011 01:51:28 +0200, Stefan Schmidt wrote:
> On Tue, Sep 20, 2011 at 11:49 AM, Peter Gervai
><grinapo+pdnsdevel at gmail.com> wrote:
>> which reminds me: is there a way to wipe the packet cache? rec_control
>> wipe-cache simply doesn't.
> It does if you specify something that it would wipe off the cache.

I don't see any evidence that it does wipe anything from the packet

E.g. do (with threads=1 to only have a single packet cache):

$ host -vt a www.powerdns.com

www.powerdns.com. 3600 IN CNAME powerdns.com.
powerdns.com. 3600 IN A

$ host -vt a Www.powerdns.com

Www.powerdns.com. 3593 IN CNAME powerdns.com.
powerdns.com. 3593 IN A

Ok, so this one must have come from the cache (as TTL < 3600).

$ rec_control wipe-cache www.powerdns.com Www.powerdns.com
wiped 1 records, 0 negative records

$ host -vt a www.powerdns.com

www.powerdns.com. 3566 IN CNAME powerdns.com.
powerdns.com. 3566 IN A

$ host -vt a www.powerdns.com

Www.powerdns.com. 3564 IN CNAME powerdns.com.
powerdns.com. 3564 IN A

Although I just wiped the cache, the responses still came from some
cache (presumably the packet cache as a dump-cache confirms that the
entry is gone there).

$ host -vt a www.powerdns.com

WWW.powerdns.com. 3600 IN CNAME powerdns.com.
powerdns.com. 3600 IN A

This finally got around the packet cache (which I guess is case
sensitive) and retrieved it again from the auth server. 



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