Wakeup is an utility that can wake up a computer within the same subnet as the initiator of this command. All what is needed is the mac address of the computer that you want to start up. A second requirment is that the destionation computer needs hardware that support wakeuplan.
1.01: Added the notation with :
Both example below wake up a computer with a network card that has the mac address 00508BCC0983. Notice that in both examples the mac address is the same only the last one has the notation with :