MAC address is always unique throughout world and can work as IMEI address of mobile set. We can trace any computer using this address. With IP address we can search the location and with MAC address we can know the exact computer.
MAC address are generally fixed but IP address may change when the network device changes from one network to another.
Find MAC address of your computer.
Click Start and go to All Programs.
Click accessories and open Command Prompt.
Type ipconfig /all and press enter.