Because without such a signal, humans using ANY for legitimate diagnostic
purposes have no means of differentiating section 4.1/4.3 "subset"
responses from conventional responses where there just happen to be only a
small number of RRSets at the queried name, encouraging (or at least doing
nothing to dissuade) a conclusion that the response is in fact conventional
and complete.

On Fri, Feb 10, 2017 at 1:44 PM, Ólafur Guðmundsson <ola...@cloudflare.com>
wrote:

> Thank you for your comments
>
> Q: why do you think it is useful to complicate things with a EDNS0 flag ?
>
> Olafur
>
>
>
> On Thu, Feb 9, 2017 at 8:47 PM, Richard Gibson <rgib...@dyn.com> wrote:
>
>> With full realization that this is coming very late in the game, we had a
>> great deal of internal conversation within Dyn about implementing
>> refuse-any, and came away unsatisfied with both the "subset" and "HINFO"
>> approaches—the latter because of reasons that have already been covered,
>> and the former for lacking in-band signaling of non-"conventional"
>> incompleteness to aid legitimate use.
>>
>> I believe there is sufficient cause to reserve a new OPT record EDNS
>> header flag bit
>> <http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-13>
>> for indicating "partial response" (as distinct from "truncation"). It will
>> be safely ignored by current clients, but convey the desired information to
>> those in the know.
>>
>> P.S. Our discussion also raised some more minor points:
>>
>>    - Insisting that the HINFO OS field SHOULD be empty ("set to the null
>>    string") seems a little too strong; there's room in it for (and value
>>    from) a short explanation (e.g., cloudflare.com. 3789 IN HINFO "Please
>>    stop asking for ANY" "See draft-ietf-dnsop-refuse-any"). I'd prefer
>>    text like "The OS field of the HINFO RDATA SHOULD be short to
>>    minimize the size of the response, and MAY be empty or MAY include a
>>    summarized description of local policy."
>>    - "Conventional [ANY] response" is used but not defined.
>>    - "ANY does not mean ALL" is misleading—RFC 1035
>>    <https://tools.ietf.org/html/rfc1035#section-3.2.3> is clear about
>>    QTYPE=255 being "a request for *all* records" (emphasis mine). That
>>    said, the proposed *response* behavior is consistent with that RFC.
>>
>>
>> On Thu, Feb 9, 2017 at 12:56 AM, <internet-dra...@ietf.org> wrote:
>>
>>>
>>> A New Internet-Draft is available from the on-line Internet-Drafts
>>> directories.
>>> This draft is a work item of the Domain Name System Operations of the
>>> IETF.
>>>
>>>         Title           : Providing Minimal-Sized Responses to DNS
>>> Queries that have QTYPE=ANY
>>>         Authors         : Joe Abley
>>>                           Olafur Gudmundsson
>>>                           Marek Majkowski
>>>         Filename        : draft-ietf-dnsop-refuse-any-04.txt
>>>         Pages           : 10
>>>         Date            : 2017-02-08
>>>
>>> Abstract:
>>>    The Domain Name System (DNS) specifies a query type (QTYPE) "ANY".
>>>    The operator of an authoritative DNS server might choose not to
>>>    respond to such queries for reasons of local policy, motivated by
>>>    security, performance or other reasons.
>>>
>>>    The DNS specification does not include specific guidance for the
>>>    behaviour of DNS servers or clients in this situation.  This document
>>>    aims to provide such guidance.
>>>
>>>
>>> The IETF datatracker status page for this draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-dnsop-refuse-any/
>>>
>>> There's also a htmlized version available at:
>>> https://tools.ietf.org/html/draft-ietf-dnsop-refuse-any-04
>>>
>>> A diff from the previous version is available at:
>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-dnsop-refuse-any-04
>>>
>>>
>>> Please note that it may take a couple of minutes from the time of
>>> submission
>>> until the htmlized version and diff are available at tools.ietf.org.
>>>
>>> Internet-Drafts are also available by anonymous FTP at:
>>> ftp://ftp.ietf.org/internet-drafts/
>>>
>>> _______________________________________________
>>> DNSOP mailing list
>>> DNSOP@ietf.org
>>> https://www.ietf.org/mailman/listinfo/dnsop
>>>
>>
>>
>> _______________________________________________
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>> DNSOP@ietf.org
>> https://www.ietf.org/mailman/listinfo/dnsop
>>
>>
>
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