A MAC address is a unique identifier assigned to network interfaces for use as a network address. MAC addresses are six groups of two hexadecimal digits separated by hyphens or colons. They are assigned by hardware manufacturers and stored in the network interface. MAC addresses operate at the data link layer and are used for communication within a network segment. The least significant bit of the first octet of a MAC address indicates whether the address is a unicast address, meant for one device, or a multicast address. Common network technologies that use MAC addresses include Ethernet, Wi-Fi, and Bluetooth.

1. MA:CA:DD:RE:SS:00
A media access control address (MAC address) is a unique
identifier assigned to a network interface controller (NIC)
for use as a network address in communications within
a network segment. This use is common in most IEEE
802 networking technologies, including ethernet, wi-fi,
and bluetooth. Within the open systems interconnection
(OSI) network model, MAC addresses are used in
the medium access control protocol sublayer of the data
link layer. As typically represented, MAC addresses are
recognizable as six groups of two hexadecimal digits,
separated by hyphens, colons, or without a separator.

2. WHAT IS AN EXAMPLE MAC ADDRESS ?
• A MAC address is a 48-bit hexadecimal address. It's usually six sets of two digits or
characters, separated by colons. An example MAC address would be 00:00:5e:00:53:af.
Many network card and other hardware manufacturers use a unique sequence at the
beginning of their products' MAC addresses.
• MAC addresses are primarily assigned by device manufacturers, and are therefore often
referred to as the burned-in address, or as an Ethernet hardware address, hardware
address, or physical address. Each address can be stored in hardware, such as the
card's read-only memory, or by a firmware mechanism. Many network interfaces,
however, support changing their MAC address. The address typically includes a
manufacturer's organizationally unique identifier (OUI). MAC addresses are formed
according to the principles of two numbering spaces based on Extended Unique
Identifiers (EUI) managed by the Institute of Electrical and Electronics Engineers (IEEE).

5. SNAP OF MAC ADDRESS ?

6. UNICAST VS. MULTICAST
• The least significant bit of an address's first octet is referred to as the I/G,
or Individual/Group, bit. When this bit is 0 (zero), the frame is meant to
reach only one receiving NIC.This type of transmission is called unicast. A
unicast frame is transmitted to all nodes within the collision domain. In a
modern wired setting the collision domain usually is the length of the
Ethernet cable between two network cards. In a wireless setting, the collision
domain is all receivers that can detect a given wireless signal. If
a switch does not know which port leads to a given MAC address, the switch
will forward a unicast frame to all of its ports (except the originating port),
an action known as unicast flood. Only the node with the matching hardware
MAC address will accept the frame; network frames with non-matching
MAC-addresses are ignored, unless the device is in promiscuous mode.

7. APPLICATIONS
• The following network technologies use the EUI-48 identifier format:
• IEEE 802 networks
• Ethernet
• 802.11 wireless networks (Wi-Fi)
• Bluetooth
• IEEE 802.5 Token Ring
• Fiber Distributed Data Interface (FDDI)
• Asynchronous Transfer Mode (ATM), switched virtual connections only, as part of
an NSAP address
• Fibre Channel and Serial Attached SCSI (as part of a World Wide Name)
• The ITU-T G.hn standard, which provides a way to create a high-speed (up to 1
gigabit/s) local area network using existing home wiring (power lines, phone lines
and coaxial cables). The G.hn Application Protocol Convergence (APC) layer accepts
Ethernet frames that use the EUI-48 format and encapsulates them into
G.hn Medium Access Control Service Data Units (MSDUs).

8. EUI-64 IDENTIFIERS ARE USED IN:
• IEEE 1394 (FireWire)
• InfiniBand
• IPv6 (Modified EUI-64 as the least-significant 64 bits of a unicast network
address or link-local address when stateless address autoconfiguration is
used.) IPv6 uses a modified EUI-64, treats MAC-48 as EUI-48 instead (as it
is chosen from the same address pool) and inverts the local bit.This results
in extending MAC addresses (such as IEEE 802 MAC address) to modified
EUI-64 using only FF-FE (and never FF-FF) and with the local bit inverted.
• ZigBee / 802.15.4 / 6LoWPAN wireless personal-area networks
• IEEE 11073-20601 (IEEE 11073-20601 compliant medical devices)

9. QUICK QUESTIONS

10. IS MAC ADDRESS SAME AS WI-FI ADDRESS?
• The "wi-fi address" you find in your Touch's settings is actually
its MAC address, a unique identifier for all network-enabled
devices. Your device only has one MAC address, but can be
given a variety of IP addresses depending on which network
you join.

11. CAN MAC ADDRESS BE CHANGED?
• The MAC address that is hard-coded on a network interface
controller (NIC) cannot be changed. However, many drivers
allow the MAC address to be changed. Additionally, there are
tools which can make an operating system believe that the NIC
has the MAC address of a user's choosing.

12. CAN 2 DEVICES HAVE THE SAME MAC
ADDRESS?
• If two devices have the same MAC Address (which occurs more
often than network administrators would like), neither
computer can communicate properly. On an Ethernet LAN, this
will cause a high number of collisions. Duplicate MAC
Addresses on the same LAN are a problem.

13. HOW DO I HIDE MY MAC ADDRESS?
• Turn off Wi-Fi when on the move. As you move around during
the day, your MAC address is broadcasted to hundreds of
networks.
• MAC spoofing. This solution will be different for every device,
but it can be one of the best ways to secure your gadgets.
• MAC randomization.

14. DOES VPN CHANGE MAC ADDRESS?
• There is no difference between the MAC address assigned by
the manufacturer of your device as well as its identity and
being changed by the VPN. Your location details are hidden by
a VPN provider. For you to connect to the internet, your MAC
address must be visible.

15. CAN SOMEONE SEE MY MAC ADDRESS?
• Nobody can see your MAC address on the Internet. Only people
on the same LAN as you can see your MAC address. (That
sometimes includes people sharing WiFi with you.) People don't
necessarily have to share the WiFi, MAC addresses sent wireless
are always visible, as long as in range of course

16. DIFFERENCE BETWEEN MAC ADDRESS AND IP
ADDRESS
S.NO MAC Address IP Address
1.
MAC Address stands for Media Access Control
Address.
IP Address stands for Internet Protocol Address.
2. MAC Address is a six byte hexadecimal address.
IP Address is either a four-byte (IPv4) or a sixteen-byte
(IPv6) address.
3.
A device attached with MAC Address can retrieve by
ARP protocol.
A device attached with IP Address can retrieve by RARP
protocol.
4. NIC Card’s Manufacturer provides the MAC Address. Internet Service Provider provides IP Address.
5.
MAC Address is used to ensure the physical address
of a computer.
IP Address is the logical address of the computer.
6. MAC Address operates in the data link layer. IP Address operates in the network layer.
7. MAC Address helps in simply identifying the device.
IP Address identifies the connection of the device on the
network.
8.
MAC Address of computer cannot be changed with
time and environment.
IP Address modifies with the time and environment.
9.
MAC Addresses can’t be found easily by a third
party.
IP Addresses can be found by a third party.

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