I know it's an odd question, but what programming language is best for networking purposes...

For what purpose exactly? Java does a pretty neat job with Networking

Sockets are sockets and should be pretty much the same in any language (including Java).

Agreed, but it would still be helpful to know what type of network programming is being considered, after all not all network programming would use sockets, (packet sniffers) and for well known tasks (web or database connections) some languages provide good wrapper functions.

It's for regular TCP sockets and UDP broadcasting.

thanks for the feedback

Personally I'd probably use Perl (without more info). It's got plenty of pre-written modules for socket handling, so you can concentrate on doing something with the data.
For low level stuff C would be the normal choice.

You will get the most efficient app with C. If you have enough time and knowledge - use C! I'd choose Java only in the "Unknown platform - client side" case. Perl is not the bad choice for the server as well, however it's still the interpreted language if your server is powerfull enough.

sockets are sockets. But not all languages support multithreading equally well. You don't mention whether you'll need more than one thread, but most network servers will use some sort of threading support to respond to multiple client requests. C/C++ wins in terms of efficiency, but the pthread library is not for the faint of heart. Java definitely has better support for synchronization and mutexes. However, in terms of high level functionality combined with adequate efficiency, why not python ("import threading").

Re Perl:

1. Threading is implemented as of 5.8 (in fact I've got/written a prog using threading and sockets in prodn).

2. Perl is not in fact interpreted; it's pseudo-compiled at startup into an executable env (see http://www.perl.com/doc/FMTEYEWTK/comp-vs-interp.html for details) and then that is run. At a guess I'd say you get 85-90% the speed of C, basically to the pt where the design/algoritm is the limitng factor, not the lang.
FYI my prog handles updating Radius accting for 5K+ cxns easily (I tested up to 20K, seemed just fine).

Nonetheless, you should pick the lang you are most comfortable with if it does threads & sockets.