Networking & Internet
MAC Address
Definition
A Media Access Control (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. It is used at the data link layer (Layer 2) of the OSI model.
Why It Matters
The MAC address is a unique, hardware-level address for a device on a local network. Switches use MAC addresses to forward frames to the correct physical device.
Contextual Example
Your laptop's Wi-Fi card has a MAC address, and its Ethernet port has another one. When you connect to your home Wi-Fi, your router keeps a table of the MAC addresses of all connected devices to know where to send traffic.
Common Misunderstandings
- A MAC address is a physical address burned into the hardware, while an IP address is a logical address that can be changed.
- A MAC address is only used for communication within the same local network. As soon as a packet goes through a router to another network, the MAC address changes.