MAC Vendor Lookup
Find the manufacturer behind a MAC address, and see whether it's a randomised address.
Worked example
A switch's MAC address table shows an unknown device on Gi1/0/14 with the address 0000.0c12.3456.
The first three octets, 00:00:0C, are an OUI registered to Cisco, so the device is Cisco equipment. An address such as 3a:1f:52:00:9b:01 has the locally administered bit set (0x3a = 00111010), so it was set by software (often a randomised Wi-Fi address) and has no vendor.
How it works
The tool takes the first three octets of the address (the OUI) and looks them up in a copy of the IEEE MA-L register. It also reads the two flag bits in the first octet: the lowest bit marks a group (multicast) address, and the next one marks a locally administered address (for a single device, one set by software).
Learn the theory
FAQ
- How does a MAC address identify the manufacturer?
- The first three octets of a burned-in MAC address are the OUI (Organizationally Unique Identifier), a block the IEEE assigns to one organisation. The manufacturer then numbers its own devices in the last three octets.
- Why does my phone's MAC address show no vendor?
- Phones and laptops often use a randomised "private" MAC address on Wi-Fi so they are harder to track. These addresses have the locally administered bit set (the second-lowest bit of the first octet), so they don't belong to any manufacturer's block.
- Why does a lookup say IEEE Registration Authority?
- Some 24-bit blocks are split into smaller MA-M and MA-S assignments for organisations that need fewer addresses. This tool uses the MA-L register of full 24-bit OUIs, so for those blocks it shows the IEEE as the holder rather than the smaller organisation.