[dns-operations] [Ext] Possibly-incorrect NSEC responses from many RSOs

Paul Vixie paul at redbarn.org
Tue Mar 2 23:35:22 UTC 2021


On Tue, Mar 02, 2021 at 07:01:10PM -0200, Viktor Dukhovni wrote:
> > On Mar 2, 2021, at 6:46 PM, Peter van Dijk <peter.van.dijk at powerdns.com> wrote:
> > 
> > Compared to REFUSED, the synthetic RRSIG has the benefit of not causing
> > a retry towards another auth (as Florian said); why not go another step
> > then and make it cacheable? You say 'no point in caching', I agree, but
> > then how about going another step and saying 'no point in a resolver
> > repeating this question on behalf of a client every second' - so put a
> > juicy TTL on it.
> 
> That way caches end up storing useless garbage, so the question is what
> to optimise for, avoiding filling caches with garbage when each query
> asks for a different name, or avoiding repeated queries for the RRSIG
> of a fixed name.  ...

caches operate at equilibrium. the working set doesn't begin to cover the
TTL before exhaustion. caching something that doesn't get reused quickly
and thereafter reused often is a zero-cost affair, it'll face discard at
a priority in keeping with its observed value. we should not reason from
"not storing useless garbage" in a world already containing wildcards and
synthesis. it's all garbage, mostly useless, and differentiating between
one kind of garbage and another is a fool's errand.

-- 
Paul Vixie


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