What is a MAC Address?
A MAC address (Media Access Control Address) is a unique identifier assigned to a network interface card (NIC) at the time of manufacturing. It is used to identify devices within a local area network (LAN) and operates at the data link layer (Layer 2) of the OSI model. Switches use MAC addresses to determine which port data should be forwarded to within the network.
A MAC address is 48 bits long and typically written in hexadecimal format, divided into six groups
Example: 00:1A:2B:3C:4D:5E
How does a MAC Address work?
When a device connects to a network, it communicates with other devices via its MAC address. Routers and switches use the MAC address to deliver packets correctly within the local network. Unlike IP addresses, which can be changed or assigned dynamically, MAC addresses are usually permanently tied to the device’s network card.
The MAC address is divided into two sections:
- OUI (Organizationally Unique Identifier): The first 24 bits identify the manufacturer
- Device-specific identifier: The last 24 bits are unique to the individual device
Why are MAC Addresses used?
- Local network communication: Enable packet delivery between devices on the same network segment
- Network control and security: Access can be allowed or blocked based on MAC addresses
- IP address management: DHCP servers can reserve specific IP addresses for devices using their MAC addresses
- Traceability and administration: Used by network administrators for troubleshooting and monitoring
Frequently Asked Questions about MAC Addresses
- How can I find a device’s MAC address?
On most computers and mobile devices, the MAC address can be found in the network settings. On Windows, use ipconfig /all, and on macOS/Linux, use ifconfig -a or ip link show. - Can a MAC address be changed?
Yes. Some devices support MAC spoofing, where the MAC address can be temporarily altered in software. - What is the difference between a MAC address and an IP address?
A MAC address identifies a physical device within the local network (Layer 2), while an IP address is used for communication between networks (Layer 3) and can change dynamically. - What is MAC filtering?
A security feature that allows or blocks access to a network based on MAC addresses. However, it is not foolproof since MAC addresses can be spoofed.