MAC Address Lookup

A MAC (Media Access Control) address is a 48-bit hardware identifier permanently assigned to a network interface card during manufacturing. Written as six pairs of hex digits (AA:BB:CC:DD:EE:FF), it operates at Layer 2 (Data Link) of the OSI model. Your router uses ARP to map IP addresses to MAC addresses within the LAN.

The first three octets (24 bits) of a MAC address form the OUI, assigned by the IEEE to manufacturers. This is why looking up "00:1A:2B" reveals the manufacturer — Apple, Cisco, Intel, etc. The remaining three octets are assigned by the manufacturer, making each MAC globally unique in theory.

IP addresses are logical, network-assigned identifiers that change as you move between networks. MAC addresses are hardware-assigned identifiers that by default remain constant. When you connect to WiFi, your MAC is visible to the access point but not to the wider internet — your router substitutes its own MAC when forwarding packets.

MAC spoofing is changing a device's MAC address in software. All major operating systems support it. Modern iOS and Android randomize MAC addresses per WiFi network for privacy. The locally administered bit (second-least-significant bit of the first octet) distinguishes randomly generated MACs from manufacturer-assigned ones.

Network admins use MAC addresses for port security, NAC (Network Access Control), and DHCP reservations. However, MAC-based security is weak alone — spoofing is trivial. It works best as one layer alongside 802.1X authentication and network segmentation.