Re: [Doh] meta qtypes

Stephane Bortzmeyer <bortzmeyer@nic.fr> Mon, 19 March 2018 09:18 UTC

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Date: Mon, 19 Mar 2018 09:16:34 +0000
From: Stephane Bortzmeyer <bortzmeyer@nic.fr>
To: Patrick McManus <pmcmanus@mozilla.com>, DoH WG <doh@ietf.org>
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References: <20180318143811.bn5kwr7oqo2ux6qm@miek.nl> <CAOdDvNoNN98zOuPAepS0=0Nt06+UAGV1ZCrxs0J2TzQaVnJz8w@mail.gmail.com> <20180318190804.5mgxarazepfut56i@miek.nl>
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Subject: Re: [Doh] meta qtypes
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On Sun, Mar 18, 2018 at 07:08:04PM +0000,
 Miek Gieben <miek@miek.nl>; wrote 
 a message of 31 lines which said:

> 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]"