Delay in named response

[Todd Pytel <tppytel_(_at_)_sophrosune_(_dot_)_org>]

Hi misc@,

I'm stumped on this one. My nameserver has been happily running 3.5
since that was released with no problems. But for the last week, I've
noticed that name resolution has been brutally slow - anything not
already in the cache takes at least 4 seconds to get a response, which
is far longer than it used to take. Running some ethereal captures on
the server's interface reveals that the actual lookups against the
outside world happen quickly (less than a second), but that my
nameserver is waiting for about 4 seconds from the time it receives the
client request until it queries an external nameserver. Like it can't
decide whether it has the query cached or not... 

Nothing in my named configuration has changed in over a month, so I
can't see what named.conf would have to do with it. Cached queries and
other connections with the server (pings, web requests, etc.) have no
problems at all, so it doesn't look to me like a hardware problem.
There's nothing unusual in any logs whatsoever. 

I'd be happy to provide any further information that would be helpful in
diagnosing this, but I don't even know where to start looking. Any
suggestions?

Thanks,
Todd Pytel