Re: [DNSOP] I-D Action: draft-ietf-dnsop-refuse-any-04.txt

Robert Edmonds <edmonds@mycre.ws> Mon, 13 February 2017 17:38 UTC

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Date: Mon, 13 Feb 2017 12:38:01 -0500
From: Robert Edmonds <edmonds@mycre.ws>
To: Richard Gibson <rgibson@dyn.com>
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Cc: Tony Finch <dot@dotat.at>, =?utf-8?Q?=C3=93lafur_Gu=C3=B0mundsson?= <olafur@cloudflare.com>, dnsop <dnsop@ietf.org>
Subject: Re: [DNSOP] I-D Action: draft-ietf-dnsop-refuse-any-04.txt
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Richard Gibson wrote:
> On Mon, Feb 13, 2017 at 11:46 AM, Tony Finch <dot@dotat.at> wrote:
> 
> > OK. But does an EDNS flag help? What if you are using old tools?
> 
> 
> If you are using old tools, then you don't get new conveniences (the same
> is true of using OPT class to specify a maximum payload size exceeding 512
> bytes, using the DO bit to request DNSSEC records, and using the COOKIE
> option for authentication). But a flag would still be there, conveying
> information even if any given client or tool isn't looking for it.

It looks like dig does display unknown EDNS flags -- as a masked hex
value:

https://source.isc.org/cgi-bin/gitweb.cgi?p=bind9.git;a=blob;f=lib/dns/message.c;h=45bd0ba9ea31be49ffa5bca2aebb77ebc2f3b95c;hb=4801fbccaa431ca6a72753150cbb58e5d4627cc4#l3408

You think this would actually provide any sort of useful information? No
operator would understand what "MBZ: 0xNNNN" means without re-training,
and if you're re-training operators you may as well point them to this
document.

-- 
Robert Edmonds