CertiGuide to A+ (Core Hardware)  9  Chapter 1011:  Networking       9  IX  Networking Devices

NIC 1 Hub -- Home of the Spokes

Every network card ever created has a unique number assigned to it (theoretically at least) called a Media Access Control (MAC) address. We say that this theoretical because some overseas manufacturers have been known to use false MAC addresses on their NIC cards. Like IP addresses, no two computers on a network can have the same MAC address.

The MAC address is a hexadecimal number, separated into two halves. The first half is a number assigned to the maker of the card, and the second half is the unique number the maker assigns that particular NIC. The theory goes that no two cards will have the same MAC address.

An IP number is bound to the MAC address. To see the MAC address that is tied to an IP address, ask the computer by issuing a request using the command Address Resolution Protocol or ARP.

If your computer says no entries, create some network activity, and type ARP again. The MAC address will be revealed.

The MAC address can be used by other hardware, such as a bridge or a switch, which will be discussed shortly.

NIC 1 Hub -- Home of the Spokes