National Datacast, Inc.

Any device whose MAC address begins with 00:21:57 has a network interface built by National Datacast, Inc.. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address.

OUI prefix

00:21:57

Organization

National Datacast, Inc.

Address

2100 Crystal Drive, Suite 750 Arlington VA US 22202

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.