What is a MAC address and how does it work?

Several Ethernet cables connected to switch ports
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If you’ve ever tried to identify devices on a network or searched for a Bluetooth device nearby, chances are you’ve managed MAC addresses. But what exactly are they and how do they differ from IP addresses?

What is a MAC Address?

Several hardware and software elements work together every day to connect us to the Internet and get data for our devices. Hardware devices such as routers and cables transmit the data we need, while software such as border gateway protocol (BGP) and internet protocol (IP) addresses direct these data packets to and from these devices. Without both working together, we could not get online.

One of these critical elements is the Media Access Control (MAC) address. MAC addresses are assigned to specific devices and assigned to them by the manufacturer.

Other names used for MAC addresses include:

  • Network hardware address
  • Burned Address (BIA)
  • Physical address
  • Ethernet Hardware Address (EHA)

Wi-Fi, Bluetooth and Ethernet connections all use MAC addresses.

MAC addresses work with the card in your device that lets it connect wirelessly to the Internet, called a Network Interface Controller (NIC). MAC addresses are used to identify which device is which on your local network so that data is sent to your computer and not your roommate’s smartphone.

MAC addresses are always a 12-digit hexadecimal number, with the numbers separated by every other digit with a colon or hyphen. So a MAC address of 2c549188c9e3, for example, would be displayed 2C: 54: 91: 88: C9: E3 or 2c-54-91-88-c9-e3.

Large network adapter manufacturers such as Dell and Cisco will often code their identifiers, called their Organizationally Unique Identifier (OUI), in the MAC addresses of devices they make. They are always the first six digits. Dells, for example, are 00-14-22.

RELATED: What is a network adapter?

How does a MAC address work?

When data packets from the Internet hit your router, that router must be able to send them to the correct device on its network. It does this using MAC addresses, and assigns a private IP address to each network-connected device based on that device’s MAC address. This is different from the IP address that your Internet Service Provider (ISP) assigns to you – it is your public IP address.

Your router tracks outbound data requests so that when the data comes back, it can attach the correct private IP to the data packets and then send them to the MAC address of the device that matches the private IP.

Devices can have more than one MAC address because they get one for each location they can connect to the Internet. For example, if your laptop has an Ethernet port and Wi-Fi, it will have different MAC addresses for the Wi-Fi connection and the Ethernet connection. Bluetooth also uses its own MAC address.

RELATED: Wi-Fi vs. Ethernet: How much better is a wired connection?

How are MAC addresses used?

In addition to sending your data to the right place, your wireless router also uses MAC addresses to secure your connection by only accepting traffic from devices with MAC addresses that it recognizes. This is called MAC filtering.

MAC addresses can also be used by technicians to troubleshoot connection problems on a network. Because they are unique to each hardware device, it is easier to determine which piece of hardware is connected to the network sending and receiving data by looking at the MAC address. From there, they can see which device is having trouble connecting.

How do I find my MAC address?

If you need to find the MAC address of your device, you can usually do so by going into the settings menu. You can follow our guide to finding the MAC addresses of your Windows device, whether you are using the Settings app or the Command Prompt.

It is also easy to find the MAC address on a Mac computer. Click the network icon in System Preferences, select the interface you want to use, and then click Advanced. You will see the MAC address listed on the Hardware tab.

Many more devices, including smart TVs, game consoles and smartphones, have their own MAC addresses that you can find.

If you want, it is also possible to change or “spoof” your MAC address.

RELATED: How (and why) change your MAC address on Windows, Linux and Mac

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