multiple queries on same ip/port quad

[Wolfgang S. Rupprecht]

Is DNS supposed to be able to cope with a resolver asking a nameserver
several UDP questions in quick succession using the same
src-ip/dest-ip/src-port/dest-port quad?

I'm seeing a case where BIND 9.2.3 appears to be turning a deaf ear
when the sender slips up and doesn't allocate a fresh src-port for
each query.

This issue turned out to be the reason why galeon and mozilla would
hang on netbsd-current.  If one clicked on a bunch of url's in quick
succession, requesting that the pages all be put in different tabs,
mozilla and galeon would just indicate "loading" forever.  When things
worked well (eg. the clicks were spaced far enough apart in time), the
resolver would allocate the next ephemeral port, one number lower than
the last one for its source port.  When things got hot and heavy, the
resolver would sometimes create the UDP socket and then switch
threads.  The next thread would also require a UDP socket, find one
open and use it.  The net effect was that several DNS queries would go
out the same socket.  Even though each DNS query had a unique DNS
transaction id, Bind would ignore all of the queries.  Now granted the
ancient netbsd resolver could use some updating to make it
thread-safe, but the question still remains, should Bind have been
able to field the queries?

-wolfgang
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