Riken Keiki Co., Ltd.

Any device whose MAC address begins with 00:21:BB has a network interface built by Riken Keiki Co., Ltd.. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address.

OUI prefix

00:21:BB

Organization

Riken Keiki Co., Ltd.

Address

2-7-6 Azusawa Itabashi-Ku Tokyo JP 174-8744

Source

IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.