Re: [DNSOP] Creating a query/record for A and AAAA

Paul Vixie <paul@redbarn.org> Tue, 03 July 2018 16:31 UTC

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Date: Tue, 03 Jul 2018 09:26:13 -0700
From: Paul Vixie <paul@redbarn.org>
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To: Ray Bellis <ray@bellis.me.uk>
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Subject: Re: [DNSOP] Creating a query/record for A and AAAA
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Ray Bellis wrote:
> On 02/07/2018 15:39, Paul Wouters wrote:
>
>> If you are trusting an unsigned A record in the answer section, you might
>> as well trust the unsigned AAAA record in the additional section too.
>>
>> I think minimum responses should still always just include this.
>
> As others have pointed out, the problem is that if you don't get the
> AAAA you can't be sure it doesn't exist (unless there's also an NSEC
> record proving it).

that's a cop-out. given negative caching both for names and rrsets, plus 
a lazy sweep-hand to semi-persistently determine the content or 
nonexistence of the rrset that wasn't available as additional data, this 
problem sorts itself at the recursive layer. and it is a non-problem for 
the authority layer.

>
> I've just refreshed my multi-qtypes draft because it was about to expire
> anyway, but also because it does include signalling to allow the client
> to differentiate between a second QTYPE that doesn't exist vs one that
> the server just doesn't have right now.

please, please, please make a document that advises authority and 
recursive server implementors to do this as additional data. do not add 
a new code-point.

-- 
P Vixie