[Pdns-users] pdns recursor edns-client-subnet caching problems

Shawn Zhou shawnzhou00 at yahoo.com
Wed Aug 9 00:07:08 UTC 2017


> On Aug 8, 2017, at 1:23 AM, Remi Gacogne <remi.gacogne at powerdns.com> wrote:
> 
> On 08/03/2017 11:05 PM, Shawn Zhou wrote:
>>> Yes, you are right, this is known behavior in 4.0.x, we don't use
>>> subnet-specific entries as soon as we get an entry usable for all subnets.
>> 
>> Will 4.0.x be updated to address the problem?
> 
> I'm not sure we should, to be honest. We could make sure that we always
> return the best match we have in cache, as 4.1 does, but it doesn't help
> much because as soon as the authoritative server sends an answer with a
> scope set to 0, we will stop asking for a better match for this
> qname/qtype until the entry expires, so you only get subnet-specific
> entries if they are inserted in the cache before the scope-0 one. This
> could make debugging quite painful.
> 
>> The 4.1 release from "http://repo.powerdns.com/ubuntu xenial-rec-41 main" didn’t work well for me because
>> I was getting timed outs. Maybe my configs need updates but they work for 4.0.
> 
> Right, we fixed some issues since alpha1, and I'm pretty sure you were
> hit by [1].

When will the next 4.1 release be available? The repo still has alpha1.

> 
>> I think your points are valid. Does PowerDNS authoritative server handles
>> this probably? If so, I like to try it out.
> 
> It is correctly handled if the backend return valid subnet information,
> yes. Please let us know if you encounter any issue.
> 
> 
> [1]: https://github.com/PowerDNS/pdns/pull/5549
> 
> -- 
> Remi Gacogne
> PowerDNS.COM BV - https://www.powerdns.com/
> 
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