DNS "protection" from PC users

[Susan Rendina <rendina@infonet1.infonet.com>]

I had asked the question recently about PCs using root servers to do
their resolution.  Thanks for all your responses. When I was explaining
the situation to my management I happened to mention that anyone 
(not only our customers) could use our DNS if they wanted to - just 
by pointing at it.  They then were all concerned and wanted to know
if I could prevent people from using our DNS without our "permission".
Is there a way to do that (without writing it myself)?  Would that even
be a nice thing to do?

Thanks,
Susan