MAC Address Explained

Summary

This video explains what a MAC (Media Access Control) address is and its role in network communication. A MAC address is a unique identifier assigned to every network device, consisting of a 6-byte hexadecimal number. It is used alongside IP addresses to enable devices to communicate, with the MAC address identifying the device and the IP address locating it. The video discusses how MAC addresses are formatted, their role in local and wide-area networks, and how devices use ARP (Address Resolution Protocol) to discover other devices' MAC addresses. It also provides a quick guide on finding MAC addresses on various operating systems.

Takeaways

• 🔑 A MAC (Media Access Control) address is a unique identifier for every network device, ensuring no two devices have the same MAC address.
• 🔢 The MAC address is a 6-byte hexadecimal number that is burned into a network interface card (NIC) by its manufacturer.
• 🧩 MAC addresses contain numbers and letters from A-F, and are divided into two parts: the first 3 bytes identify the manufacturer, and the last 3 bytes uniquely identify the device.
• 🖥️ MAC addresses are displayed differently on different systems: Windows uses dashes, Linux/Apple systems use colons, and Cisco uses periods.
• 🌐 MAC addresses allow network devices to communicate with each other, whether on the same network or over long distances.
• 🆔 Unlike IP addresses, which can change, MAC addresses are permanent and tied to the hardware.
• 📡 Devices use both MAC and IP addresses to communicate: the IP address locates the device, while the MAC address identifies it.
• 🏡 A MAC address can be compared to a person's name, while an IP address is like the address of a house, helping devices find each other on the network.
• 🚪 Communication between devices on the same network uses ARP (Address Resolution Protocol) to find the MAC address of the recipient.
• 🔄 Data sent across networks uses MAC addresses at every step as it passes between routers, with each router needing the MAC address of the next hop in the path.

Q & A

What is a MAC address?

A MAC address, or Media Access Control address, is a unique identifier assigned to network devices to identify them on a network.

How is a MAC address formatted?

A MAC address is a 6-byte hexadecimal number that can contain numbers and letters from A to F, and is typically formatted with colons, dashes, or periods depending on the operating system.

What are the two parts of a MAC address?

The first 3 bytes of a MAC address identify the manufacturer of the network interface card (NIC), while the last 3 bytes are a unique number assigned to the specific device by the manufacturer.

How do MAC addresses differ from IP addresses?

MAC addresses are permanent and used to uniquely identify devices, whereas IP addresses can change and are used to locate devices on a network.

What role does the MAC address play in device communication?

The MAC address is used in local and wide-area communication to allow devices to send and receive data to and from each other.

What is ARP (Address Resolution Protocol) and how is it related to MAC addresses?

ARP is a protocol used by devices to discover the MAC address of other devices on the same network. A device sends an ARP broadcast to ask for the MAC address of another device before communication begins.

What happens when a device on a local network wants to communicate with another device?

The device checks if the other device is on the same network by inspecting its IP address. If they are on the same network, the first device uses ARP to find the second device's MAC address and initiate communication.

How does a device communicate with a device on a different network, like google.com?

The device first resolves the domain (e.g., google.com) into an IP address using DNS. Then, it sends data to its default gateway (router), which forwards the data across routers using MAC addresses at each step until it reaches the destination.

Can a computer have more than one MAC address?

Yes, a computer can have multiple MAC addresses depending on how many network interfaces it has, such as for wired, wireless, and Bluetooth adapters.

How can you find the MAC address on a Windows or Linux/Mac computer?

On Windows, you can find the MAC address by opening a command prompt and typing 'ipconfig /all'. On Linux and Mac, you can open a terminal and type 'ifconfig'.

Outlines

00:00

💻 What is a MAC Address?

A MAC address, or Media Access Control address, is a unique identifier assigned to every network device, ensuring no two devices share the same address. It is a 6-byte hexadecimal number embedded into the network interface card (NIC) by the manufacturer. The first three bytes indicate the manufacturer (e.g., Linksys, TP-Link), while the last three bytes uniquely identify the device. The MAC address is also referred to as the physical or hardware address and is formatted differently on various systems like Windows (with dashes), Apple/Linux (with colons), and Cisco (with periods). Its primary purpose is to allow devices to communicate on the network.

05:02

🌍 MAC Address vs. IP Address

The MAC address allows devices to communicate over the network, whether they are on the same or different networks. While the MAC address remains permanent, IP addresses can change periodically. Both the IP and MAC addresses work together for successful communication. The MAC address identifies the device, while the IP address locates it. An analogy: the IP address is like the mailing address of a house, and the MAC address is like the name of the person inside.

🔄 How Devices Communicate Using MAC Addresses

When two devices, such as Computer A and Computer B, communicate on a local network, Computer A inspects Computer B's IP address to confirm they are on the same network. It then uses the ARP (Address Resolution Protocol) broadcast to obtain Computer B's MAC address. Once the MAC address is known, communication occurs. If the devices are on different networks (e.g., Computer A and a Google web server), Computer A forwards data to the router via an ARP broadcast, which repeats until the data reaches its final destination.

🌐 Role of MAC Addresses Across Different Networks

When devices are on different networks, as with Computer A accessing Google's web server, the MAC address is crucial for data transmission between routers. Each router involved in the path to the destination needs the MAC address of the next device in line. Using ARP broadcasts, routers continually request MAC addresses to forward data to the next router until it finally reaches the web server. In this process, the IP address helps locate the destination, while the MAC address ensures data is forwarded between each intermediary device.

🔧 Finding Your MAC Address

To find the MAC address on a computer, users can use specific commands: on Windows, it’s 'ipconfig /all' and on Linux/Mac, it’s 'ifconfig.' A computer can have multiple MAC addresses, depending on how many network interfaces (e.g., wired, wireless, Bluetooth) it has. The video also encourages users to explore related topics like ARP and default gateways in other videos for deeper understanding of network communication.

Keywords

💡MAC Address

A MAC (Media Access Control) address is a unique identifier assigned to each network interface card (NIC) by its manufacturer. It is a 6-byte hexadecimal number that helps devices identify each other on a network. The MAC address is permanent and used in communication at the data link layer. In the video, the MAC address is compared to the name of a person living in a house.

💡IP Address

An IP (Internet Protocol) address is a unique identifier used to locate a device on a network. Unlike MAC addresses, IP addresses can change periodically, depending on the network's configuration. The video explains that an IP address works in tandem with a MAC address, serving as the mailing address of a device, while the MAC address identifies the specific device.

💡NIC

A Network Interface Card (NIC) is the hardware component within a device that allows it to connect to a network. Each NIC comes with a unique MAC address, assigned by the manufacturer. In the video, the MAC address is described as being 'burned into' the NIC, making it an essential part of the device's ability to communicate.

💡ARP

Address Resolution Protocol (ARP) is a network protocol used to map an IP address to a MAC address. When a device needs the MAC address of another device on the same network, it sends out an ARP broadcast. The video mentions ARP in the context of Computer A trying to find Computer B's MAC address to initiate communication.

💡Default Gateway

A default gateway is the router or network node that a device uses to send data to another network. It acts as an intermediary when a device on one network needs to communicate with a device on another. The video explains how Computer A, when communicating with a remote server like Google, forwards data to its default gateway.

💡Router

A router is a networking device that forwards data between different networks. It uses IP and MAC addresses to determine the best path for data to reach its destination. The video describes how routers help forward data from one network to another, with each router needing the MAC address of the next one in the chain.

💡DNS

Domain Name System (DNS) translates human-readable domain names (like google.com) into IP addresses that computers can use. The video highlights DNS in the context of Computer A converting 'google.com' into an IP address to communicate with Google's server.

💡Hexadecimal

Hexadecimal is a numbering system used in MAC addresses, consisting of digits 0-9 and letters A-F. Each MAC address is made up of 6 bytes, displayed in this format, which helps uniquely identify devices. The video explains that the MAC address can include both numbers and letters in this format.

💡TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is the fundamental communication protocol suite used for interconnecting network devices on the internet. It requires both an IP address and a MAC address for devices to communicate. The video touches on this when explaining how devices need both identifiers to talk to each other.

💡Network Interface

A network interface refers to any point where a device can connect to a network. Each network interface has a unique MAC address. The video explains that a computer can have multiple MAC addresses if it has multiple network interfaces, such as wired, wireless, or Bluetooth adapters.

Highlights

MAC (Media Access Control) address is a unique identifier assigned to every network device, ensuring no two devices have the same MAC address.

A MAC address is made up of a 6-byte hexadecimal number, containing numbers and letters from A to F, and is burned into the network interface card (NIC) by its manufacturer.

The first 3 bytes of a MAC address identify the NIC's manufacturer, while the last 3 bytes are a unique number assigned by the manufacturer to identify each device.

MAC addresses are also referred to as physical or hardware addresses and are formatted differently depending on the system: with dashes on Windows, colons on Linux and Apple, and periods on Cisco devices.

The primary purpose of the MAC address is to allow devices to communicate with each other on the same or different networks, using MAC addresses for direct communication.

While public IP addresses can change over time, MAC addresses are permanent and never change, making them a consistent identifier for network devices.

TCP/IP, the language of networks and the internet, requires both IP and MAC addresses: the MAC address identifies the device, and the IP address locates the device.

An IP address is like a mailing address that locates a device, while a MAC address is like the name of the person using the device.

When devices on the same local network communicate, the IP address helps identify if they're on the same network, but the MAC address is used for actual communication.

Devices use ARP (Address Resolution Protocol) to broadcast and request the MAC address of another device on the same network.

For communication between devices on different networks, the MAC address of the router (default gateway) is used to forward data between networks.

When accessing a website like google.com, DNS translates the domain to an IP address, which helps the computer route data, while routers along the path use ARP to request the MAC addresses of the next router in the sequence.

At every step of the data transmission process, MAC addresses are used for communication between devices and routers, while the IP address locates the final destination.

A computer can have multiple MAC addresses, depending on how many network interfaces it has, such as wired, wireless, and Bluetooth adapters.

To find a MAC address, users can run 'ipconfig /all' on Windows or 'ifconfig' on Linux and Mac systems to see the physical address of each network interface.

Transcripts

What is a MAC address?

So that is the topic of this video.

Now the MAC or media access control address is an identifier that every network device

uses to uniquely identify itself on a network.

So no 2 devices anywhere in the world will have the same MAC address.

The MAC address is made up of a 6 byte, hexadecimal number that is burned into every NIC by its

manufacturer.

The MAC address can contain any number and it also contains alphabets from A - F

The MAC address is broken up into 2 parts.

The first 3 bytes identify the manufacturer of the NIC, such as Linksys, Netgear, TP-link, etc.

The last 3 bytes are a unique number from the manufacturer that

identifies each device on a network.

The MAC address is also referred to as the physical address or hardware address.

MAC addresses are formatted in different ways.

On a windows computer, it will look like this, with dashes in between the digits.

On Apple and Linux systems, it will have colons in between the digits.

And Cisco will display the MAC address like this, where 4 sets of digits are separated by periods.

So what exactly is the purpose of the MAC address?

The purpose of the MAC address is so network devices can communicate with each other.

Whenever a device wants to talk to another device, it's ultimately done using the MAC address.

And this is whether the devices are close to each other, such as being on the same network,

or if they are thousands of miles apart on a different network.

The bottom line is that devices communicate with each other using the MAC address.

Now you might be asking yourself, well if devices talk to each other using the MAC address.

What is the purpose of an IP address?

I mean aren't IP addresses also unique?

Well public IP addresses are unique. But public IP addresses can periodically change.

So you may have had a certain IP address for the past few months, but an internet service provider or

a network administrator can change your IP address to a different one.

But MAC addresses don't change. They are permanent.

Now the way TCP/IP works, which is the language that's used on networks and the internet

a networking device needs both an IP address and a MAC address. The IP and MAC addresses

work together so devices can talk to each other.

So as I stated before, the MAC address is used to identify a device, but an IP address

is used to locate that device.

So for example in a typical neighborhood, you have houses and you have people living in those houses.

Each house has a mailing address and the person living inside has a name.

An IP address is like the mailing address of a house. The mailing address tells us what

country, city, and the street of where the house is located. But it doesn't necessarily

tell us who lives in the house.

But a MAC address is like the name of the person. It tells us who lives in the house.

So an IP address tells us where a networking device is located.

But a MAC address tells us specifically who the device is.

So as I stated before the MAC address is ultimately used when devices want to talk to each other.

So here we have a local area network that you would find in a typical home or business.

So let's say that computer A wanted to communicate with computer B on this local network.

So computer A is going to inspect computer B's IP address to see if it's on the same

network or not.

So after inspection, computer A now knows that computer B is on the same network because the

IP addresses are in the same group.

So now in order for communication to take place.

Computer A needs computer B's MAC address and it finds this by sending what's called an

ARP or address resolution protocol broadcast.

So it will broadcast to every device on its local network, asking computer B to identify

itself by asking for its MAC address. Then once computer B tells computer A its MAC

address, communication can finally take place.

So in another scenario, what if 2 devices wanted to communicate with each other but

they are on different networks. So let's say that computer A wanted to go to google.com.

Now in order for computer A to go to google.com it needs the MAC address for Google's web server.

But the problem is, is that it doesn't know what it is. So this is why it needs the IP address

to get the web server's MAC address.

So computer A will type in google.com in its web browser and then DNS will change google.com

into an IP address so computers can understand it.

So computer A will inspect Google's IP address and realize that the IP is not in its local

network because the IP address is not in the same group as its local network.

So now computer A realizes that Google's IP address is on a different network and since it's on

another network it's going to forward the data to its default gateway which is the router and

then it will let the router deal with it.

So again computer A will send out an ARP broadcast and this time it will ask for the

MAC address of the default gateway. Then once it has the MAC address it will send

the data to the default gateway.

Then once the default gateway has the data it will inspect Google's IP address and determine

the best path for the data to reach the destination.

So it will forward the data to the next router. But before it can forward the data it also

needs the next router's MAC address. So it's also going to do an ARP broadcast and ask

for that router's MAC address Then once it has it, it will forward the data.

And then that router needs the MAC address of the next router, and so on.

Then once the data reaches the final router in its path, that router needs the MAC address

of Google's web server. And then once it has it, the data has reached its final destination.

So as you can see each time data is passed between a computer or a router

device it uses the MAC address to forward the data at each step.

So to summarize, the IP Address is used to locate and get to the final destination.

But the MAC address is used at each step on its way to the final destination

Now if you want to find the MAC address of a computer, this is how you do it.

So on a Windows computer, you just open up a command prompt and type ipconfig /all.

On Linux and MAC computers, you open up a terminal and type ifconfig.

So here is our MAC address for this Windows computer and as you can see it's listed as

the physical address.

Now a computer can have more than one MAC address.

It just depends on how many network interfaces it has.

So for example this computer has 3 MAC addresses.

This one here is for the wired network adapter.

This one here is for the wireless network adapter. And this one here is for the bluetooth

network adapter.

Now if you want to know more about this topic, I highly recommend you watch a couple of my

other videos.

Such as my ARP video, because it will explain a little more details about ARP, especially

about the ARP cache and how it works. And I also recommend my default gateway video

Because it will explain how devices know if IP addresses are in the same local network or group

or if they're on a different network.

So I want to thank you for watching this video on MAC addresses.

Please subscribe and I will see you in the next video.