MAC Address Generator

A MAC address is a link-layer identifier commonly represented as 12 hexadecimal digits, such as AA:BB:CC:DD:EE:FF. Network interfaces may have a factory-assigned address, a configured address, or a temporary randomized address. Switches and access points use it to deliver frames on the local link.

In a classic 48-bit MA-L assignment, the first 24 bits identify an IEEE-assigned organization and the organization assigns the remaining bits. IEEE also offers other assignment block sizes, and locally administered addresses do not identify a vendor. A prefix can help create realistic test fixtures, but it does not prove who made a device.

The second-least-significant bit of the first octet is the U/L flag. A value of 1 marks an address as locally administered rather than globally assigned by the IEEE. This avoids claiming a vendor prefix, but it does not guarantee uniqueness among other locally generated addresses. Check for collisions within the network where you use it.

Colon notation is common on Unix-like systems, hyphen notation is common on Windows, and dotted notation is common in Cisco tooling. Raw notation removes separators. Use the format required by the specific command, API, or configuration field because parsers do not all accept every form.

Use it for test fixtures, isolated labs, simulations, or systems that explicitly require you to assign a local address. Do not introduce generated addresses into a production network without collision checks and authorization. Phones, virtual machines, and operating systems may also generate locally administered addresses using their own policies.