MAC Address (Media Access Control address) is a 48-bit hardware identifier burned into every network interface — Ethernet card, Wi-Fi radio, Bluetooth chip. It’s the physical-layer address used by switches and access points to deliver frames within a local network. It is not used for internet routing.
Format
d4:81:d7:2c:5f:8a
D4-81-D7-2C-5F-8ASix pairs of hex digits, separated by colons or hyphens. Total 48 bits = 12 hex characters.
Structure
- First 24 bits — OUI (Organizationally Unique Identifier), assigned by IEEE to the manufacturer
- Last 24 bits — assigned by the manufacturer to the specific unit
Looking up the OUI portion reveals the device manufacturer (Apple, Cisco, Samsung, Intel, etc.).
MAC vs IP
- MAC — physical, permanent, layer-2 (Ethernet)
- IP — logical, assignable, layer-3 (internet)
A device has one MAC per network interface, and one or more IP addresses per interface. MAC gets your packet across the local Wi-Fi; IP gets it across the internet.
Privacy: MAC Address Randomization
Modern operating systems (iOS 14+, Android 10+, Windows 10+, macOS Sonoma) randomize their Wi-Fi MAC per SSID. Prevents tracking by MAC address across coffee shops, airports, etc.
Lookup
DomainScan’s MAC address lookup tool resolves the OUI portion to a manufacturer name — useful for identifying unknown devices on a network.
Related
Check the OUI glossary entry, read the What Is a MAC Address? deep dive, and check the Port 25 glossary entry for another common network identifier.