Hi Ed,
Thanks for this info, very useful to those who were at v6ops during the 6man 
meeting.
Reactions below to some quoted sentences.

1.
"Yahoo's worry is that some operating systems issue quad-A records by default, 
even if the user has broken IPv6 connectivity and needs single A records to 
access IPv4-based content."
"Work with OS/app vendors to fix IPv6 issues – Awful long lead times/upgrade 
cycles"
"This is a really ugly hack, but it may be necessary to get widespread IPv6 
adoption,"
=> If there are indeed OS bugs that break connectivity, they should justify 
quick patches like those that concern security. 

2.
"Gashinsky adds that Yahoo is conducting its own analysis of broken IPv6 
connectivity, which it will share with the Internet engineering community in 
June."
=> As a minimum, what the problem really is should be documented before 
proposing to adopt any solution to solve it, in particular if it is "ugly".

3.
"Only way of knowing the user has working IPv6 connectivity, is if the AAAA 
query came over IPv6!"
=> This DOESN'T WORK :
- Today, dual-stack hosts on Free's network query Free's DNS in IPv4 (at the 
only DNS address they know, received in DHCPv4)
- These hosts, because they have valid IPv6 addresses (i.e. have IPv6 enabled), 
ask for both As and AAAAs.
- For maps.google.fr, for example, BOTH types of RRs are in the DNS.
- They are included in DNS responses
- Hosts then use IPv6 (preferred in case of choice).

4.
"Return 0 answers for AAAA if, and only if: - Query comes over Ipv4; - “A” 
record exists for same name; - DNSSEC is not used."
=> This hack would NOT ONLY be "ugly" (as acknowledged by their proponents), 
BUT ALSO would BREAK some of the IPv6 connectivities that are available today 
!!!

==> This hack MUST therefore be flatly rejected.


If and when the mentioned OS problems are documented, it will be possible to 
fix them with patches in OSes, where they belong.

RD



Le 30 mars 2010 à 00:21, Ed Jankiewicz a écrit :

> Probably no one on either of the IPv6 lists attended the DNSOPS WG meeting in 
> Anaheim, since it was at the same time as 6man.
> 
> Presentation by Yahoo! of a proposal to "do an ugly hack on DNS" to work 
> around an issue with "broken OSes" that send out AAAA requests when they have 
> no intention/ability to actually use an IPv6 address.  Google experience is 
> that a small percentage of their users would lose connectivity because of 
> this, if google.com serves both IPv6 and IPv4 addresses.  I can't recall if 
> this particular issue has been discussed here, but either way anyone with an 
> interest should probably pop comments over to the DSNOPS WG list.
> 
> http://www.ietf.org/proceedings/10mar/slides/dnsop-7.pdf
> 
> Also FYI - this has gotten press coverage, not necessarily accurately 
> characterizing the problem or proposed solution
> 
> http://www.networkworld.com/podcasts/360/2010/032910-nw360-daily.html
> http://www.networkworld.com/news/2010/032610-dns-ipv6-whitelist.html
> 
> -- 
> Ed Jankiewicz - SRI International
> Fort Monmouth Branch Office - IPv6 Research Supporting DISA Standards 
> Engineering Branch
> 732-389-1003 or  ed.jankiew...@sri.com 
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> IETF IPv6 working group mailing list
> ipv6@ietf.org
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