MAC Address stands for Media Access Control Address. It is an unique identifier which is brunt in on Network Interfaces Cards (NIC) and being used for host identification and communication between multiple hosts on a Local Area Network (LAN). MAC addresses live at Layer 2 of the OSI Model.

MAC is also known as Hardware Address or Physical Address. It has total address space of 48 bits which can create 2^48 or 281,474,976,710,656 possible MAC Address.  One can think of a MAC address as the street address, town, state and zip code.  Each are unique and enable clear distinct communications with end points.

MAC Addresses are 12-digit hexadecimal numbers with dash, colon, or period notation.

• OO-OO-OO-HH-HH-HH
• OO:OO:OO:HH:HH:HH
• OOOO.OOHH.HHHH

First 24-Bit (3 Octates) of MAC Address shows the Organizational Unique Identifier (OUI) / Vendor Identifier and the other half shows the Hardware Serial Number.  You can use an OUI lookup tool to determine who made the NIC card, WireShark OUI Lookup Tool.

• Microsoft Windows
• MAC OS X

MACOSX~user$ ifconfig

lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384

options=3<RXCSUM,TXCSUM>

inet6 ::1 prefixlen 128

inet 127.0.0.1 netmask 0xff000000

inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1

nd6 options=1<PERFORMNUD>

gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280

stf0: flags=0<> mtu 1280

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500

ether 20:c9:d0:88:74:89 

inet6 fe80::22c9:d0ff:fe87:7989%en0 prefixlen 64 scopeid 0x4

inet 192.168.75.250 netmask 0xffffff00 broadcast 192.168.75.255

nd6 options=1<PERFORMNUD>

media: autoselect

status: active

• LINUX

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