When computers are, connect on any network a network card is used, known as NIC card which is having a MAC address. This address is use to distinguish one system from another we may say that it is the physical address given by the manufacturer to provide a unique identity to equipment. We have studied that MAC address is permanent and cannot be changed but there are different ways in which MAC address of equipments could be changed whether it is a pc/laptop or mobile. We could use wire shark to know the changed MAC address of any system for which the packet is been send or received. The change in MAC is called MAC spoofing, which is having advantages as well as disadvantages