Locally administered addresses set the U/L bit so they won’t collide with burned-in vendor OUIs — preferred for VMs, containers, and lab bridges.

Vendor-prefixed mode uses your OUI for the first 3 octets and randomizes the rest (still unicast). These are for testing only — don’t spoof production hardware identities on networks you don’t control.

Want the manufacturer for an address? Use MAC Address Lookup.