MAC address stands for Media Access Control address. This is the unique identifier that is assigned to network interfaces used for communications accessing the physical network segment. Majority of IEEE 802 network system as well as the Ethernet use MAC addresses as a network address. In essence, MAC address is used in the MAC protocol sub-layer for the OSI reference type.
A MAC address is usually assigned by the NIC manufacturer and store it on the network interface controller’s hardware either on other firmware mechanism or on the NIC card’s read only memory. Each NIC contains one unique MAC address.
MAC addresses are more useful and handy for security purposes because these addresses are not often changed from its default setting. On the other hand, IP addresses can dynamically changed particularly those who are part of a network that uses DHCP system to assign IP addresses automatically. This is one of the main reasons why MAC addresses provides a more reliable way to identify and recognize senders as well as receivers of network traffic.
When it comes to wireless networks, filtering of MAC address is a common security practice in order to inhibit unauthorized network access. To filter MAC addresses, the router for the wireless network is configured to receive traffic only from specific MAC addresses. For this, while a white listed device is assigned with a new IP address via DHCP, a MAC address retains its capacity to communicate using that network. An intruder who will attempt to imitate a valid user that is part of that said network by using a fake IP address will not be able to gain access because the MAC address of the computer will not match those addresses included in the white list. But on the other hand, this type of security measure can only offer minimal success because a well experienced intruded can always find a way to face a valid MAC address just like changing an IP address. But still it provides an additional amount of security for those fake addresses that blindly join a network system.