If you’ve ever tried to use Wake-on-LAN technology, you may know that its configuration can be confusing sometimes. You have to enable WOL in BIOS and motherboard settings and correctly specify the WOL command parameters. Wake-on-LAN utilities (see a review for one of them) usually allow waking up one remote PC and require that you specify its IP and MAC addresses in order to generate and send a magic packet to it. In order to wake up multiple PCs, you have to write scripts to detect MAC addresses of remote PCs and execute a WOL utility to send the magic packet to every PC. A free Wake-on-LAN tool from EMCO is specially designed to wake up multiple remote PCs and allows automating all required operations.
Source : 4sysops.com