Clients get DNS timeouts because ipv6 means more queries for each lookup

[Mark Andrews]

In message <4E1B5C57.8090100 at kamens.us>, Jonathan Kamens writes:
> On 7/11/2011 4:06 PM, Bill Owens wrote:
> > https://lists.isc.org/pipermail/bind-users/2011-March/083109.html
> >   in which the first sentence says it all: "The nameservers for wikiped=
> ia.org are broken."
> It's not just wikipedia.org that's broken, obviously. I see this error
> in my logs for 19 domains since July 3:

Well you havn't been looking at your logs or you upgraded to a version
which logs the condition.
 
> Even if PowerDNS is the only source of this issue, and even if the new
> version of PowerDNS is released tomorrow, I'm sure there will still be
> sites running the old version a year from now. So just relying on a
> PowerDNS release to fix this problem seems unwise.

Sure, but it is a minor issue overall.  FORMERR is a lot better
that what used to happen.  Nameservers used to drop AAAA queries
so you got timeouts when all the nameseservers were working instead
of when some are working.

> Users are experiencing this problem /now/ in the field, and more users
> will be experiencing it as BIND is upgraded in more and more places.
> Every single user relying on a Fedora 15 DNS server, for example, is
> going to see occasional unnecessary DNS timeouts when trying to resolve
> host names.

Well complain to the owners of those zones.  You have logs that tell you
which nameservers are broken.

> It seems clear to me that a generally available, generally applicable
> fix to BIND is needed to avoid this issue and perhaps similar issues
> like it.

The DNS has multiple nameservers so that when one is down you can
ask another and be able to cache the answer.  Here none of the
nameservers are giving answers that can be cached.  FORMERR, NOTIMP,
REFUSED/timeout are per server not per query tuple <QNAME/QTYPE/QCLASS>.

>    jik
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org