Re: [DNSOP] [Ext] I-D Action: draft-ietf-dnsop-svcb-https-05.txt

John R Levine <> Thu, 13 May 2021 04:43 UTC

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Date: 13 May 2021 00:43:36 -0400
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From: "John R Levine" <>
To: "Ben Schwartz" <>, "Brian Dickson" <>
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Subject: Re: [DNSOP] [Ext] I-D Action: draft-ietf-dnsop-svcb-https-05.txt
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>> (The history of SMTP is, I think, a good poster child for this, with MX,
>> A, AAAA, plus DNSSEC and TLSA support in the clients, which are email
>> transport things, not merely DNS things.)

Not really.  MX and A mean different things, and it is useful and common 
for an SMTP server to be pointed to via MX and A with different names.

> The SVCB parameters' wire format is an extremely simple TLV arrangement; I
> don't think "a complex parser" is required.  It's also far from a novel
> design for DNS; in fact, it's identical to the widely implemented OPT RR
> RDATA format from 1999 [1][2].

Having written some DNS parsers, I agree.  Parsing the fields out of the 
wire format is easy.  I have reservations about SVCB but the encoding 
is not one of them.

John Levine,, Taughannock Networks, Trumansburg NY
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