FYI. I once proposed this in draft-davey-sunset4-ipv6onlydns-00.
3.2. IPv6-aware DNS Referral Response Mechanism
In section 2.2, due to the limitation of DNS referral response size,it may
occur that when new NS server updated to IPv6, the address cannot be carry in
the referral response in the first place without EDNS0 support. It may deliver
the incomplete view of IPv6 Internet to IPv6 only recursive server and
IPv6-only users. For example, the Root zone and any zones with more than 9-10
authority server may face the problem.
One intuitive thinking is that if the query is on IPv6 connection, the IPv6
addresses should be carried with high priority in DNS response if there is not
enough room for all the NS RR. For example, as a key internet public services,
IPv6 addresses of root name servers will be entirely contained in the referral
response over IPv4 address information in dual-stack environment.
Davey
-----
Sent from my phone
---Original---
From: "Tony Finch"<d...@dotat.at>
Date: 2015/10/16 18:04:48
To: "Mark Andrews"<ma...@isc.org>;
Cc: "dnsop WG"<dnsop@ietf.org>;"Paul Hoffman"<paul.hoff...@vpnc.org>;
Subject: Re: [DNSOP] Closing out issues in draft-ietf-dnsop-resolver-priming
Mark Andrews <ma...@isc.org> wrote:
> In message <8149bc4d-f11e-4e4f-bbb8-c38d865a4...@vpnc.org>, "Paul Hoffman"
> writ
> es:
> >
> > If the response packet does not provide for more than 512 octets due
> > to lack of EDNS0 support, A RRSets SHOULD be given preference over
> > AAAA RRSets when filling the additional section.
>
> I would recommend that the transport family used to make the query
> should be the determining factor for which additional records are
> dropped.
I was going to make the same point :-)
> > What to do with payload sizes indicated by
> > EDNS0 that are smaller than 1024, is open to discussion.
Do the same thing with or without EDNS0.
> > At the time
> > of writing, some root name servers will fill the additional section
> > with all available A RRSets, only adding some AAAA RRSets, when
> > queried over IPv4 without EDNS0.
They have the same behaviour (prioritize A) when queried on IPv6.
Tony.
--
f.anthony.n.finch <d...@dotat.at> http://dotat.at/
Lundy, Fastnet, Irish Sea: Northeast 4 or 5. Slight or moderate, but smooth or
slight in Irish Sea. Fair. Good.
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