I was planning on solely using its output to determine which PCs were on the network. After a little bit of use, I noticed that it isn't always up to date. PCs that were off but now on, sometimes show as off.. and sometimes PCs that were on and now off, show as still on.

Is there a reason for this, such as it's source of information updated only once every 30 minutes or something? Would there be an easy/quick function to correctly obtain the PCs that are currently on and connected to the LAN?