Mark Andrews wrote:
In message<56e83f6e.2040...@redbarn.org>, Paul Vixie writes:
an authoritative nxdomain proves that there is nothing below that qname.
this obviates all prior positive responses for that qname -- you
wouldn't say that we should continue to send positive responses for
other data perhaps based on qtype as a differentiator, because the
definition of nxdomain is qtype-independent, i.e., it applies to a name.
If proves that from the instance of the zone as served by that
server at that time. It says zero about latest zone as that cache
has no way to learn if the answer is from the latest zone.
Removing cached records assumes the NXDOMAIN response is from the
latest zone. Now that may well be a reasonable assumption to make
but we need to acknowledge that it is a assumption.
if that assumption weren't also being made by all implementations of
negative caching to date, and was thus not specific to the subdomain
clarification for nxdomain treatment, i'd agree, we ought to mention it.
instead i'll say, perhaps it's time to revise RFC 2308 along these
lines. i think a higher cost system than DNS which was willing to trade
resources to get coherence, all answers would be SOA.SERIAL tagged.
--
P Vixie
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