firefox hangs while trying to resolve hosts

[Tom McLaughlin]

Hi all, I've been having some problems with firefox (mozilla appears to
do this as well) on certain websites with them taking significant
periods of time for their address to be resolved.  This doesn't seem to
be a network issue on my end since while a site is hanging on this
machine, I can bring up the same page on my openbsd machine running
firebird 0.6 almost instantaneously.  What I've done is create a few
packet captures with ethereal for a site that hangs firefox a lot
(www.allmusic.com)[1], a site that generally doesn't hang
(www.freebsd.org)[2], and the site that hangs on freebsd but not on
openbsd[3].

What I noticed is in [1] multiple type AAAA queries are made which
eventually receive back a "Server failure" response and then an ICMP
unreachable packet.  A type A query is finally made after some time
which responds fine.

In [2] the type AAAA query is responded to fine and then there is a type
A query.

In [3] there are only type A queries made.

Something more is that if I click stop in firefox as a site is hanging
and then try to go to another site I will still see dns queries for the
hanging site continued to be made.  Eventually those will stop and I
will start seeing queries for the new site.  Please let me know if I can
provide anything more.  I didn't have this problem in 0.7.  Thanks.

Tom

OS: 4.9-RELEASE-p3
IP: 192.168.1.128 (fbsd), 192.168.1.129 (obsd)
DNS: 204.127.204.8, 216.148.227.204

[1] http://tmclaugh.freeshell.org/files/www.allmusic.com.pcap
[2] http://tmclaugh.freeshell.org/files/www.freebsd.org.pcap
[3] http://tmclaugh.freeshell.org/files/www.allmusic.com-obsd.pcap
(I've scrubbed out a bit of the unrelated network noise in all three.)