An interface to a network from a computer or server or printer (or really
anything that connects to a network) that interface enables that computing device
to send and receive data across the network. It's typically referred to as
the "network interface" All modern computing devices have a network
interface either wired to connect to an Ethernet network using Ethernet cables
like these or wireless to connect to a wireless Access Point (AP). The network
interface traditionally has been called a Network Interface Card or NIC for
short NIC because the interface in most older machines up to this point
came on a separate expansion card. However for many years now motherboards
of both laptops and desktops have "onboard" or rather built-in network
interfaces. Most texts today still call them NICs whether they're built-in or
whether they're an actual separate card that's used on the motherboard of a
server or a PC or a printer. This is a picture of an onboard NIC that's already
built into the motherboard for a desktop PC just gave me give you a little bit of
an idea of how that looks. There are several responsibilities that
NICs have: They provide connection to the network media of course (either network
cables or wires or wireless using radio frequency waves or they could be
Bluetooth, etc.) they provide connectivity. NICs also have a physical address known
as a MAC address that stands for Media Access Control which I'm going to show
you and talk more about shortly in this same video
these NICs enable communication with other devices on the network.
Finally NICs take data from the operating system and they encapsulate
that data into a frame suitable for traversing that physical layer that
physical aspect of the network whether that's the cable or the wireless. In fact
if and when you study the 7 layers of the OSI model or the layers of the
TCP/IP model, you need to know upfront that most of the
work that takes place in those layers working together is really all done
within that NIC and it's usually its onboard processor chip or chips that do
all that work with the with the layers of the OSI model or the layers of the
TCP/IP model. More on that in other videos and in the bonus section of the
free mini course if you manage to take advantage of getting access to that. So
let's talk about the MAC address on every NIC. The analogy that's usually
used with MAC addresses and IP addresses in the networking field is that they are
similar to the name of a student in a classroom - that's always the analogy
that's used. The teacher and the other students in that classroom may not know
how to find or address one another if they don't have a name for each other if
they don't know what to call each other. So each person has a name each student
and the teacher or teachers have a name. A MAC address is the same as the name
hard assigned to each NIC card or each NIC interface on a motherboard. On every
NIC burned onto a ROM chip is special firmware containing a unique identifier
with a 48 bit value called the Media Access Control address or MAC address
for short. No 2 NIC's ever share the same MAC address EVER! Any company that
makes NIC's that manufactures them must contact the Institute of Electrical and
Electronics Engineers (also known as IEEE) and request a block of MAC
addresses which that company then burns into the ROMs or the ROM chips on its
NIC's. Many NIC makers also print the MAC address on the surface of each NIC
like you see here. MAC addresses are written with a hexadecimal digit because
each hex character represents 4 bits each and it takes 12 hex characters to
represent 48 bits. The MAC address on this NIC card shown here is 004
005A7BA71 Although in print we represent the
MAC address 00 - 40 - 05 - A7 - BA - 71 we
put hyphens between every two hexadecimal characters in that MAC
address. The first 6 digits in this example 00-40-05
represent the number of the NIC manufacturer. Once the IEEE issues
those 6 hex digits to that manufacturer often called the
Organizationally Unique Identifier (or OUI) no other manufacturer may use
those 6 digits in that order. The last 6 digits in this example are A7-BA-71
Well those are the manufacturers unique serial number for that specific
NIC. This portion of the MAC address is often called the "Device ID" so the first
half is the OUI first half the MAC address is the OUI the Organizationally
Unique Identifier and the last half the last 6 digits is the Device ID for
that specific NIC card. Would you like to see the MAC address for your NIC on
the computer that you're on now? If you have a Windows system search for the
command line program you can search for CMD also called a Command Line Interface.
And once that text command program is open
it'll look similar to this you're going to type in "ipconfig /all"
and hit ENTER. You're going to do that from the command prompt to display
the MAC address like you see here. Now note that in the IE config output the
MAC address is always called the "physical address" that's how it's
referred to when you reference it on a computer like this. So that's the basic
functions of the NIC card and what we're referring to when we talk about the MAC
address on a computing device or any device connected to a network.