minor tangent: source of queries

[Ian Watts]

While inspecting the traffic on my busiest nameserver, I discovered that
one busy webserver in the same facility was regularly hitting the
nameserver with up to 45 identical queries in a span of 40 ms.  This box
accounts for about 25-55% of all queries to the nameserver.

So my question is whether or not people may have already identified likely
software problems/issues that could account for this.  In my case, it's a
web server running (gasp!) Netscape Enterprise Server 3.62. I don't
control that box and I can't access it, but I'd like to be able to tell
the people who DO control it how they can significantly reduce nameserver
activity as well as network traffic in general. 

These query blasts are always for PTR records.  The web server is an E250
running some version of Solaris.  The nameserver averages about 200-450
queries per second.

Anyone have any suggestions?  Is this perfectly normal?

TIA,

-- Ian Watts