MAC Address Lookup Methodology

1. Normalisation

The web tools convert letters to uppercase and remove separators. Colon, dash, Cisco dot, space-separated and plain hexadecimal formats therefore produce the same lookup key.

2. Address classification

The second-least-significant bit of the first octet is the universal/local bit. If it is set, the web tool returns Locally administered, because the registered prefix may not identify the underlying hardware. Randomised Wi-Fi and virtual interfaces commonly use this bit.

The least-significant bit of the first octet is separate: it distinguishes an individual address from a group (multicast) address. A multicast address is not automatically locally administered.

3. Longest-prefix matching

For other addresses, the service checks the most specific IEEE assignment first: a 36-bit MA-S prefix, then a 28-bit MA-M prefix, and finally a 24-bit MA-L or CID prefix. A match returns the organisation name recorded for that assignment; otherwise the tool reports that the vendor was not found.

How to interpret a match

A registry match associates a prefix with an organisation. It is not proof of a device model, ownership, location or current operator. See data sources and coverage for the current snapshot, registry types, and record count.