The MAC Addressing And Spoofing

      The MAC address is "Media Access Control " address which is the unique identifier assigned to network interface cards(NICs) by the manufacturer for the purpose of identification. It may also known as an Ethernet Hardware Address, Adapter Address or Hardware Address.
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. The second half of a MAC address represents the serial number assigned to the adapter by the manufacturer.

In the example,

00:A0:C9:29:B8:36

The prefix 00A0C9 indicates the manufacturer is Intel Corporation.

MAC Spoofing is a technique of changing an assigned Media Access Control (MAC) address of a networked device to a different one. The changing of the assigned MAC address may allow the bypassing of access control list on servers or routers either hiding a computer on a network or allowing it to impersonate another computer.
MAC spoofing is the activity of altering the MAC address of network cards .
In windows change of MAC address can be change by editing the registry or via "My Network Places" . To change the MAC address via Network Places
go to properties of "local Area Connection", press configure.. button then go to advance tag
In advance tag select Local Administrative Address ,
select value radio button and insert any MAC address you want.
To alter the MAC via the registry, open the Windows Registry Editor and change the appropriate values.
The value " NetworkAddress" is located in a subkey under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}.