[dns-operations] resolver cache question

Florian Weimer fw at deneb.enyo.de
Fri Nov 13 23:07:13 UTC 2020

* Mark Allman:

>> One could use a Bloom filter to avoid caching (most) lookup
>> results that are encountered just once.  Or start out with an
>> artifically lowered TTL combined with prefetching.
> I am not sure what you mean.  If a given lookup isn't in a bloom
> filter, add it to the bloom filter and if it is cache it?

Add it to the Bloom filter and do not cache it otherwise.  If it's
already in the filter, cache it.

>> The authoritative server operators know that their zones are used
>> for what is essentially an RPC.  Don't they set a zero TTL?
> No.  The first paper I cited says in their dataset the one-time
> lookups have TTLs on the order of 600sec (on median or something I
> can't quite recall).  So, non-trivial.

Ah, that's not good.

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