Re: [dnsext] draft-vixie-dnsext-resimprove - NXDOMAIN for emptynon-terminals

----- Original Message ----- 
From: "Edward Lewis" <Ed.Lewis@neustar.biz>
To: <dnsext@ietf.org>
Cc: "Edward Lewis" <Ed.Lewis@neustar.biz>
Sent: Tuesday, March 29, 2011 3:45 PM
Subject: Re: [dnsext] draft-vixie-dnsext-resimprove - NXDOMAIN for emptynon-terminals

> At 15:03 +0100 3/29/11, George Barwood wrote:
> 
>>What is the motive for this "trick"? Saving bandwidth??
> 
> There are zones which do not exist in total at any given point in 
> time.  These are zones that do not conform to a zone "file" and 
> cannot be represented in an AXFR.  For these zones, a statement of 
> what exists can be made "locally" but generating a "universal" list 
> would be impossible.  Answering only the query at hand is the concern 
> because the current protocol rules say caches don't synthesize 
> answers from what they cache.  (They can repeat answers in the cache, 
> not synthesize them.)

I agree it's quite common for zones to give non-deterministic positive answers
as a form of load-balancing, where a limited set of A records is randomly 
(or otherwise) selected from a large set. This is not affected.

It's quite hard to see how it could be useful to have inconsistent NSEC bitmaps though.
Can you give any kind of hypothetical use case?

George

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> Edward Lewis
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