How can I check if a computer on my network is online?

Question

I want to know how to check if a machine on my network is online, using only C#.

All machines on my network use the same OS (Windows 7) and I'm logged in as the same user on all machines.

My goal is to check if they are active, or open.

Answer 1

Simple:

Ping ping = new Ping();
PingReply pingReply = ping.Send("ip address here");

if(pingReply.Status == IPStatus.Success)
{
   //Machine is alive
}