Re: [Doh] meta qtypes

Miek Gieben <miek@miek.nl> Mon, 19 March 2018 09:49 UTC

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Date: Mon, 19 Mar 2018 09:49:12 +0000
From: Miek Gieben <miek@miek.nl>
To: Stephane Bortzmeyer <bortzmeyer@nic.fr>
Cc: Patrick McManus <pmcmanus@mozilla.com>, DoH WG <doh@ietf.org>
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Subject: Re: [Doh] meta qtypes
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[ Quoting <bortzmeyer@nic.fr> in "Re: [Doh] meta qtypes..." ]
>> I think this draft should say "MUST not cache these responses".
>
>I have a less radical proposal:
>
>"DoH servers SHOULD return a Cache-Control header (RFC 7234, section
>5.2.2). They MAY send "Cache-control: no-cache" in all cases [if
>they're lazy]. For positive
>answers (ANCOUNT>0), if the DoH server returns "Cache-control:
>max-age=N", the maximum age MUST be the TTL of the answer seen by the
>Doh server. For negative answers (NXDOMAIN), if the DoH server returns "Cache-control:
>max-age=N", the maximum age MUST be calculated from the SOA record of
>the zone (RFC 2308, section 3) [note it allows a server to return
>"Cache-control: no-cache" only for NXDOMAIN]"

I agree that this works (but still leaves out RRSIGs).

The (major) downside is that a DoH server doesn't just ship bytes anymore; it 
need to fully inspect the payload to make an informed cache TTL decision.

Note: I'm fine with either - nocache or something along the lines Stephane 
proposes.

/Miek

--
Miek Gieben