Which company owns MAC address prefix 40:2F:51?

MAC address prefix 40:2F:51 is registered to Maxtek Optoelectronics Ltd in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:2F:51 has a network interface built by Maxtek Optoelectronics Ltd.

What is the OUI 40:2F:51?

40:2F:51 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Maxtek Optoelectronics Ltd. It covers every address from 40:2F:51:00:00:00 to 40:2F:51:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-2F-51.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 40:2F:51:00:00:00 that is 40:2F:51 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is Maxtek Optoelectronics Ltd located?

Maxtek Optoelectronics Ltd is listed at 8 Wing Hong Road Kowloon HK 000000 in the IEEE OUI registry entry for 40:2F:51. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Maxtek Optoelectronics Ltd

MAC address prefix 40:2F:51 is registered to Maxtek Optoelectronics Ltd in the IEEE OUI registry. Any device whose MAC address begins with 40:2F:51 has a network interface built by Maxtek Optoelectronics Ltd. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 40:2F:51:00:00:00 to 40:2F:51:FF:FF:FF.

OUI prefix: 40:2F:51
Hyphen form: 40-2F-51
MAC range: 40:2F:51:00:00:00 – 40:2F:51:FF:FF:FF
Addresses in block: 16,777,216
Organization: Maxtek Optoelectronics Ltd
Address: 8 Wing Hong Road Kowloon HK 000000
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.

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2025-02-27Assigned to "Maxtek Optoelectronics Ltd"
archived source →
2026-07-17Assigned to "Maxtek Optoelectronics Ltd"

Nearby in the registry

The prefixes assigned immediately before and after 40:2F:51:

FAQ

Which company owns MAC address prefix 40:2F:51?: MAC address prefix 40:2F:51 is registered to Maxtek Optoelectronics Ltd in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:2F:51 has a network interface built by Maxtek Optoelectronics Ltd.
What is the OUI 40:2F:51?: 40:2F:51 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Maxtek Optoelectronics Ltd. It covers every address from 40:2F:51:00:00:00 to 40:2F:51:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-2F-51.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 40:2F:51:00:00:00 that is 40:2F:51 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is Maxtek Optoelectronics Ltd located?: Maxtek Optoelectronics Ltd is listed at 8 Wing Hong Road Kowloon HK 000000 in the IEEE OUI registry entry for 40:2F:51. This is the address the organization registered with the IEEE, which may differ from its current operating address.