a *fast* check for whether another machine is on the local network?

[Dar Scott]

> What I'm really looking at is a laptop that spends some of its time in
> the office, but also goes to court, where an attorney may want to make
> time entries.
> 
> At that point, I'd like the laptop to simply figure out where it is
> without waiting for a timeout.

Windows has this swoon-awful concept of recognizing networks by patterns in the network.  Well, the notion is not awful, just Windows policy.  You might be able to tap into that.

If you know that the subnets are going to be different, you can find the IP address of the laptop and see which network it is on.  If this looks like the right way for you, then ask.  

There are other things you can try depending on how specific or how general the situation is.  If the computer is the dhcp server or something, there are ways.

Dar