Honeywell

Any device whose MAC address begins with C4:EF:DA has a network interface built by Honeywell. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address.

OUI prefix

C4:EF:DA

Organization

Honeywell

Address

9680 Old Bailes Rd, Fort Mill, SC 29707 Fort Mill SC US 29707

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.