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MAC Address

A MAC address is the 48-bit hardware address of a network interface card (e.g., 00:1A:2B:3C:4D:5E) that identifies the device at the link layer; the OUI is assigned by IEEE.

Purpose

It uniquely identifies a network interface at the LAN link layer for frame addressing.

Mechanism

The 48 bits split into an OUI (first 24 bits, assigned by IEEE to the vendor) and a NIC-specific part (last 24 bits). It is written in colon- or hyphen-separated hexadecimal. The first bit is I/G (unicast/multicast) and the second U/L (global/local). EUI-64 extends it to 64 bits for IPv6.

Use cases

  • Ethernet frame addressing
  • ARP resolving target MACs
  • Bluetooth device pairing
  • Network access control

Examples

  • Input 
    00:1A:2B:3C:4D:5E
    Output 
    OUI 00:1A:2B identifies the vendor

    48 bits

Common errors

MAC addresses can be spoofed (no authentication)
Use 802.1X port-based authentication

Related terms

IP Address
An IP address is the numeric identifier assigned to a network interface—32 bits for IPv4 (four decimal octets) and 128 bits for IPv6 (eight hexadecimal groups)—used for network addressing.
GLOSSARY
IPv6
IPv6 is the 128-bit network addressing protocol, written in colon-separated hexadecimal (e.g., 2001:db8::1), offering about 3.4×10^38 addresses to solve IPv4 exhaustion.
GLOSSARY

Related tools

MAC Address Tool
Validate MAC addresses, convert between separator formats, toggle case, and look up vendor via OUI prefix. Free, private, and 100% client-side.
TOOL
Mac To Ip
Mac To Ip — pure client-side tool. Privacy-first, no server round-trip.
TOOL
Ip To Mac
Ip To Mac — pure client-side tool. Privacy-first, no server round-trip.
TOOL
Vendor To Mac
Vendor To Mac — pure client-side tool. Privacy-first, no server round-trip.
TOOL
Mac To Vendor
Mac To Vendor — pure client-side tool. Privacy-first, no server round-trip.
TOOL

References