[6bone] www.6bone.not

[Stewart Tansley]

> As I have IPv6 installed WinXP decided to resolve www.6bone.net to its
IPv6 address, and as I never had a tunnel configured it wouldn't reach
it.
>
> Question for Stuart then, 
> This could present a problem for lots of Microsoft users if they have
XP with (accidentally or not) the IPv6 stack installed. Even if a v4
version of a site exists, it will not be looked for as the v6 address of
the site has not been reached, by default it seems that if a v6 version
exists it will look for that and if not found will return an error.

Gav -- IE6 does fall back to using IPv4 if the IPv6 connection is
unsuccessful.

IE6 (and other IPv6-savvy Windows apps) explicitly queries for both AAAA
and A records from the DNS via the stack's call to the DNS client. The
combined results from the DNS server are returned to the app in a list.
It is the apps responsibility to cycle through the list. IE6 is written
to do this correctly (i.e. try IPv6 addresses first, then IPv4), so it
should by design fall back to using IPv4 if the IPv6 connection fails
for some reason. If this is apparently not happening, it is likely a
problem with either *both* transports to the web site, or the DNS server
you are querying is not returning both AAAA and A records correctly. We
have seen some of the latter.

Stewart Tansley
Program Manager
http://www.microsoft.com/ipv6/