What Is a MAC Address?
A MAC (Media Access Control) address is a unique 48-bit hardware identifier assigned to every network interface card (NIC). The first 24 bits (3 bytes) form the Organizationally Unique Identifier (OUI), which identifies the manufacturer. This tool looks up the OUI to determine the vendor.
MAC Address Formats
- Colon-separated: 00:1A:2B:3C:4D:5E (Linux, macOS)
- Dash-separated: 00-1A-2B-3C-4D-5E (Windows)
- Dot-separated: 001A.2B3C.4D5E (Cisco)
- Bare: 001A2B3C4D5E
Unicast vs. Multicast
The least-significant bit of the first octet determines the cast type. If it's 0, the address is unicast (destined for a single device). If it's 1, it's multicast (destined for a group). The second-least-significant bit indicates whether the address is universally or locally administered.