Subject: Re: Issue: Add a new QTYPE

From: Paul Vixie <[email-masked]>
Date: Wed, 19 Nov 2003 17:18:14 +0000

> ...
> The namedroppers archives contain plenty os material on just why meta
> queries don't work, so I don't think we need to repeat it all here.

there's meta and then there's meta.  had we specified that AAAA responses
had additional data processing of the form "add any matching A RRsets"
then a single AAAA query, either to an authority or a cache, would give
us all of the data we'd want in one query.  (note that these would be 
added even if the AAAA response set was empty.)

it's not too late for that by the way.

> A more feasible (but still not easy) solution to the problem raised,
> as much as it actually is a problem, is to do one query with multiple
> questions.   That doesn't really work with standard DNS that's deployed,
> but can be made to work with suitable levels of EDNS added in (I forget
> which EDNSn is required for it nor if it is even agreed yet).

it was part of edns1 as proposed, but that was shot down as "too complex"
because of the other things that had to be optioned (like first match vs.
all matches, and recursive vs. really recursive).

my strong recommendation is still that we include A RR's in the additional
data section of any response to AAAA.  then if clients who want "whichever
exists" or even "both if possible" simply ask for AAAA first, and if they
happen to be talking to an aaaa-additional-a capable server, they can get
what they want in one RTT.  when talking to older servers they still have
to pay two RTTs but that's no worse than today.

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---

From: Paul Vixie <[email-masked]>
Date: Wed, 19 Nov 2003 19:12:18 +0000

> ...
> That might work, if we can get enough servers to actually implement it.
> But it is a short term hack, which we'd need to eradicate eventually,
> and that's one reason I don't think it is a good idea.

for it to be a short term hack in need of eventual eradication, there
would have to be a large difference in expected lifetime between "names
for which A RR's exist" and "clients who need A RR's".  i think that
those two lifetimes are in the same rough order of magnitude, and that
by the time you'd be thinking of eradicating it because the additional
data wasn't generally useful, the data itself would go into end-of-life.

> ...
> Bill - I can't even begin to imagine what discover has to do with any
> of this.

agreed.  DISCOVER is about finding servers, not finding answers.