[Pdns-users] Query throttled message in pdns_recursor trace log

Remi Gacogne remi.gacogne at powerdns.com
Thu Aug 16 07:47:15 UTC 2018


On 8/15/18 10:36 AM, hariesfa wrote:
> I assume this mechanism is a feature that powerdns has, to protect
> server resources. But, is there a way to reconfigure this throttling
> mechanism ? I have tried to decrease server-down-throttle-time by hoping
> that once the authoritative answered my query, powerdns will keep the
> record in its cache.

You can indeed try tuning server-down-throttle-time and
server-down-max-fails, but these servers are so broken that it seems to
me that the result will always be impossible to predict.
You are right, however, if we somehow manage to get the answer at least
once, we will keep it in cache for a while, depending on the TTL and
your cache settings.
> Because, if i try to use other dns recursor software, they can resolve
> this domain.

Some recursor implementations are known to try very hard to resolve
broken domains, and sometimes they manage to. PowerDNS Recursor, on the
other hand, tries not to waste resources dealing with clearly broken
domains and/or servers, and we have seen time and time again that it
makes a lot of difference in resource-constrained situations, like when
you are under some kind of attack.

Best regards,
Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/

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