OPTEC DAIICHI DENKO CO., LTD.

Any device whose MAC address begins with 00:40:39 has a network interface built by OPTEC DAIICHI DENKO 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

00:40:39

Organization

OPTEC DAIICHI DENKO CO., LTD.

Address

FIBER OPTICS & TELECOM. DIV. JAPAN

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.