IPv6 and email routing, was Re: AAAA records to be added for root servers
Tony Finch <dot@dotat.at> Mon, 07 January 2008 19:44 UTC
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Date: Mon, 07 Jan 2008 19:43:58 +0000
From: Tony Finch <dot@dotat.at>
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To: John C Klensin <john-ietf@jck.com>
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Cc: ietf@ietf.org, Bill Manning <bmanning@ISI.EDU>
Subject: IPv6 and email routing, was Re: AAAA records to be added for root servers
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On Fri, 4 Jan 2008, John C Klensin wrote: > On Friday, 04 January, 2008 12:01 -0800 Bill Manning <bmanning@ISI.EDU> wrote: > > > > The general answer when needing to communicate between similar > > applications that run on different address families has traditionally > > been the application layer gateway (ALG) ... MTAs *are* ALGs. > [...] If the MX resolution doesn't work smoothly for IPv6, then the DNS > isn't IPv6-ready no matter how many AAAA records are defined and spread > around. [...] I hope the additional information rules have been adjusted > if needed to encourage return of relevant AAAA records if they exist > [...] Yes AAAA records are returned in the additional section just like A records. However this behaviour is less useful than one would hope, because of the RFC 2181 rules about the TC bit. In particular, it is not set when RR sets have been dropped from the additional section of the reply. This means an MTA can't immediately tell the difference between an IPv4-only MX record and a dual-stack MX record where the IPv6 addresses have been truncated. It must do extra DNS lookups to resolve the ambiguity, which (at the present time) is usually a waste of effort. The extra lookups are not optional because you can also get dual-stack MX replies in which the A records have been dropped, which can (and does) lead a naive IPv4-only MTA to think erroneously that it cannot reach the other server. Tony. -- f.a.n.finch <dot@dotat.at> http://dotat.at/ NORTH FITZROY: SOUTHWESTERLY 6 TO GALE 8, PERHAPS SEVERE GALE 9 LATER. VERY ROUGH. RAIN. MODERATE. _______________________________________________ Ietf mailing list Ietf@ietf.org https://www1.ietf.org/mailman/listinfo/ietf
- RE: AAAA records to be added for root servers Hallam-Baker, Phillip
- Transitioning to IPv6 == dual-stack (Re: AAAA rec… Jeroen Massar
- AAAA records to be added for root servers Barbara Roseman
- Re: AAAA records to be added for root servers John C Klensin
- Re: AAAA records to be added for root servers Bill Manning
- Re: AAAA records to be added for root servers John C Klensin
- Re: AAAA records to be added for root servers Iljitsch van Beijnum
- Re: AAAA records to be added for root servers Franck Martin
- Re: AAAA records to be added for root servers John C Klensin
- Re: AAAA records to be added for root servers Bill Manning
- Re: AAAA records to be added for root servers Franck Martin
- Re: AAAA records to be added for root servers John C Klensin
- Re: AAAA records to be added for root servers Brian E Carpenter
- Re: AAAA records to be added for root servers Bill Manning
- Re: AAAA records to be added for root servers Iljitsch van Beijnum
- Re: AAAA records to be added for root servers John C Klensin
- Re: AAAA records to be added for root servers Masataka Ohta
- Re: AAAA records to be added for root servers Iljitsch van Beijnum
- Re: AAAA records to be added for root servers Brian E Carpenter
- Re: AAAA records to be added for root servers Mark Andrews
- RE: AAAA records to be added for root servers Hallam-Baker, Phillip
- RE: AAAA records to be added for root servers Pasi.Eronen
- Re: AAAA records to be added for root servers Bill Manning
- Re: [apnic-talk] AAAA records to be added for roo… Jeffrey A. Williams
- Re: AAAA records to be added for root servers Iljitsch van Beijnum
- IPv6 and email routing, was Re: AAAA records to b… Tony Finch
- Re: IPv6 and email routing, was Re: AAAA records … Jeroen Massar
- IPv6 and email routing, was Re: AAAA records to b… Tony Finch
- Re: IPv6 and email routing, was Re: AAAA records … Tony Finch
- IPv6 and email routing, was Re: AAAA records to b… Tony Finch
- Re: AAAA records to be added for root servers SM
- Re: IPv6 and email routing, was Re: AAAA records … Franck Martin
- Re: AAAA records to be added for root servers Brian E Carpenter
- Re: IPv6 and email routing, was Re: AAAA records … Dave Crocker
- Re: IPv6 and email routing, was Re: AAAA records … John C Klensin
- Re: IPv6 and email routing, was Re: AAAA records … Dave Crocker
- Re: IPv6 and email routing, was Re: AAAA records … Tony Finch