Strange: My Bind (8.4.6) freezes randomly

[David Nolan]

--On Wednesday, January 10, 2007 17:21:38 +0100 Santiago Romero 
<sromero at servicom2000.com> wrote:

>   Suddenly, since 4th January 2007 we have strange problems with the
> named/bind daemon. It's working perfectly until randomly it freezes.
> DNS querys continue arriving to the machine but bind doesn't resolve
> them. I can't even solve queries launched from the own machine:


Were any changes made to the system on or around that date?

This sounds a lot like a problem I had a while back which turned out to be 
a kernel bug in Linux 2.6.14 where a zero length UDP packet would generate 
an error on the socket, resulting in bind no longer processing that socket.

Two symptoms I noticed in my case were:

- queries to other IP addresses on the same server would work, including 
localhost.  What happens if you dig @127.0.0.1?

- strace'ing the named process I saw it iterating over the sockets calling 
select on each one, until the failure point, at which point the primary udp 
socket was no longer being selected.  What do you see if you strace the 
process?

(In my case, upgrading to 2.6.16 solved the problem.)

-David Nolan
 Network Software Designer
 Computing Services
 Carnegie Mellon University