[ratelimits] Remarks regarding the Knot DNS 1.2.0 RRL implementation

Paul Vixie paul at redbarn.org
Thu Mar 7 01:12:37 UTC 2013

Marek Vavruša wrote:
> On 6 March 2013 05:36, Paul Vixie <paul at redbarn.org> wrote:
>> ...
>> in bind9 there's a 32 bit hash of the qname in each chained bucket. that's a
>> far larger collision domain than you'll see in an unchained hashing scheme.
>> so my answer to your question is: "it depends on the size of the collision
>> domain".
>> paul
> I agree, so should we update the memo to reflect that? This collision
> rate is is more than acceptable,
> I just pointed to the fact that the memo mandates perfect mapping and
> then we get to a situation when
> neither one implements it because it's not (from my point of view) required.

this is an excellent observation.

> Personally, I would leave it open to implementation, but then we get
> into the debate about if "far larger" is enough or how bad is "quite
> small" or other uncertain terms.

i think the spec should recommend some minimum sized collision domain,
and it should require that collisions be detected and reported, and that
the result of a collision should be described as "will cause bucket
reset, thus opening the possibility of false negatives".

what do you think about this?

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