sub.dom with cached NXDOMAIN dom

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D. J. Bernstein

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Dec 7, 1999, 3:00:00 AM12/7/99
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Here are three ways to use a recently cached NXDOMAIN foo.bar IN A:

(1) Respond NXDOMAIN for any IN query within the foo.bar domain.
(2) Respond NXDOMAIN for any IN query for the name foo.bar.
(3) Respond NXDOMAIN for any IN A query for the name foo.bar.

RFC 2308 recommends #2. It doesn't mention #1 or #3. Is this choice
based on some unpublished statistics on caching effectiveness? Or did
RFC 2308 actually mean to recommend #1?

---Dan


Paul A Vixie

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Dec 8, 1999, 3:00:00 AM12/8/99
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NXDOMAIN's scope is the {name,type}. RFC 2308 implicitly outlawed BIND's
behaviour, which is to return NOERROR/ANCOUNT=0 for empty nonterminals.
After RFC 2308, empty nonterminals are signalled with NXDOMAIN. Therefore
#1 would be incorrect. #3, while correct, would waste information since
NXDOMAIN signals "no RRs of any type at this name".


Paul A Vixie

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Dec 8, 1999, 3:00:00 AM12/8/99
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{name,class}, yes. oops.

> To: Paul A Vixie <vi...@mibh.net>
> From: "Matt Crawford" <cra...@fnal.gov>
> Subject: Re: sub.dom with cached NXDOMAIN dom
> In-reply-to: Your message of Tue, 07 Dec 1999 23:00:54 PST.
> <1999120807...@bb.rc.vix.com>
> Date: Wed, 08 Dec 1999 12:56:41 -0600
> Sender: cra...@gungnir.fnal.gov


>
> > NXDOMAIN's scope is the {name,type}. RFC 2308 implicitly outlawed BIND's
>

> Did you mean {name,class}?


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