What is a MAC Address? Physical Network Identification
Discover what Media Access Control addresses are, how they differ from IP addresses, and their role in local networks.
Key Takeaways
- •A MAC address is a permanent physical identifier assigned to a network interface controller (NIC).
- •Unlike IP addresses, MAC addresses do not route across the internet; they are strictly local.
- •The first half of a MAC address identifies the hardware manufacturer (OUI).
Physical Hardware Identification
A Media Access Control (MAC) address is a unique 48-bit identifier burned into the read-only memory of a network adapter during manufacturing. It is usually represented as six groups of two hexadecimal digits (e.g., 00:1A:2B:3C:4D:5E).
MAC vs. IP Addresses
While an IP address is used to route data across the global internet (Layer 3), a MAC address is used to deliver data between devices on the exact same local network segment (Layer 2). When data arrives at your home router via your public IP, the router uses ARP (Address Resolution Protocol) to find the specific MAC address of the laptop or phone that requested the data.
Manufacturer Codes (OUI)
The first 24 bits (the first three octets) of a MAC address constitute the Organizationally Unique Identifier (OUI). This prefix is assigned by the IEEE and can be used to identify the specific manufacturer of the network card, such as Intel, Apple, or Cisco.
Frequently Asked Questions
Can my MAC address be tracked online?
No. Your MAC address never leaves your local network. Websites you visit can only see your router's public IP address, not the MAC address of your specific device.