Friday, August 5, 2011

What Is a MAC Address?

The MAC address is a unique value associated with a network adapter. MAC addresses are also known as hardware addresses or physical addresses. They uniquely identify an adapter on a LAN.
MAC addresses are 12-digit hexadecimal numbers (48 bits in length). By convention, MAC addresses are usually written in one of the following two formats:
MM:MM:MM:SS:SS:SS

 
MM-MM-MM-SS-SS-SS
The first half of a MAC address contains the ID number of the adapter manufacturer. These IDs are regulated by an Internet standards body (see sidebar). The second half of a MAC address represents the serial number assigned to the adapter by the manufacturer. In the example,
00:A0:C9:14:C8:29
The prefix
00A0C9
indicates the manufacturer is Intel Corporation.

 

 
MAC vs. IP Addressing
Whereas MAC addressing works at the data link layer, IP addressing functions at the network layer   (layer 3). It's a slight oversimplification, but one can think of IP addressing as supporting the software implementation and MAC addresses as supporting the hardware implementation of the network stack. The MAC address generally remains fixed and follows the network device, but the IP address changes as the network device moves from one network to another.
IP networks maintain a mapping between the IP address of a device and its MAC address. This mapping is known as the ARP cache or ARP table.
Find MAC Address of your Computer
  1. Click on the Start Menu.
  2. Click on 'Run & Type 'cmd' without quotes and press Enter.
  3. At the command prompt, type 'ipconfig /all' without quotes. (space between g and /)

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