FC5 i386 or x86_64 which way to go?

[Michael Cohen]

On Thu, Sep 21, 2006 at 10:45:22PM -0400, Glen Turner wrote:
> Now that's interesting, since we designed the protocol so that
> there would be no additional delay.  A ANY query should return
> the AAAA and the A.  A failing AAAA query should return any
> matching A record in the Additional Records.

I think thats correct. The problem is however in older dns servers which just
ignore questions for records they dont understand - which leaves the resolver
to time out.

Although Im not on such a network at the moment, a quick google shows an RFC
which illustrates the issue: http://www.rfc-archive.org/getrfc.php?rfc=4472

<quote>
   There are several classes of misbehavior in certain DNS servers and
   load-balancers that have been noticed and documented [RFC 4074]: some
   implementations silently drop queries for unimplemented DNS records
   types, or provide wrong answers to such queries (instead of a proper
   negative reply).  While typically these issues are not limited to
   AAAA records, the problems are aggravated by the fact that AAAA
   records are being queried instead of (mainly) A records.

   The problems are serious because when looking up a DNS name, typical
   getaddrinfo() implementations, with AF_UNSPEC hint given, first try
   to query the AAAA records of the name, and after receiving a
   response, query the A records.  This is done in a serial fashion --
   if the first query is never responded to (instead of properly
   returning a negative answer), significant time-outs will occur.
</quote>

I noticed however that current implementations (im on ubuntu 6.06 now) issue
both A and AAAA requests almost simulateneously which may be a way for them to
test the ability of the DNS server to handle AAAA. That among other workarounds
are suggested in the RFC as well - so it may not be such an issue with more
recent system.

This issue was particularly very disappointing when trying to demo linux for
non-techy people who would install it at home and come back with a "linux is
just sooo slooowww" remark. Of course they had no idea about dns or AAAA
records - nor did they care. I think that linux distributions embraced ipv6 too
early to make it a system default. Although windows has IPv6 support, its not
turned on by default afaik.

Michael.