Which company owns MAC address prefix 28:1D:21?

MAC address prefix 28:1D:21 is registered to IN ONE SMART TECHNOLOGY(H,K,)LIMITED in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 28:1D:21 has a network interface built by IN ONE SMART TECHNOLOGY(H,K,)LIMITED.

What is the OUI 28:1D:21?

28:1D:21 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to IN ONE SMART TECHNOLOGY(H,K,)LIMITED. It covers every address from 28:1D:21:00:00:00 to 28:1D:21:FF:FF:FF, or 16,777,216 addresses in total. It is also written 28-1D-21.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 28:1D:21:00:00:00 that is 28:1D:21 — 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 IN ONE SMART TECHNOLOGY(H,K,)LIMITED located?

IN ONE SMART TECHNOLOGY(H,K,)LIMITED is listed at UNIT I 1/F MAU LAM COMM BLDG 16-18 MAU LAM ST JORDAN KL HK HONGKONG HK 999077 in the IEEE OUI registry entry for 28:1D:21. This is the address the organization registered with the IEEE, which may differ from its current operating address.

IN ONE SMART TECHNOLOGY(H,K,)LIMITED

MAC address prefix 28:1D:21 is registered to IN ONE SMART TECHNOLOGY(H,K,)LIMITED in the IEEE OUI registry. Any device whose MAC address begins with 28:1D:21 has a network interface built by IN ONE SMART TECHNOLOGY(H,K,)LIMITED. 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 28:1D:21:00:00:00 to 28:1D:21:FF:FF:FF.

OUI prefix: 28:1D:21
Hyphen form: 28-1D-21
MAC range: 28:1D:21:00:00:00 – 28:1D:21:FF:FF:FF
Addresses in block: 16,777,216
Organization: IN ONE SMART TECHNOLOGY(H,K,)LIMITED
Address: UNIT I 1/F MAU LAM COMM BLDG 16-18 MAU LAM ST JORDAN KL HK HONGKONG HK 999077
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.

2022-07-11Assigned to "IN ONE SMART TECHNOLOGY(H,K,)LIMITED"
archived source →
2026-07-17Assigned to "IN ONE SMART TECHNOLOGY(H,K,)LIMITED"

Nearby in the registry

The prefixes assigned immediately before and after 28:1D:21:

FAQ

Which company owns MAC address prefix 28:1D:21?: MAC address prefix 28:1D:21 is registered to IN ONE SMART TECHNOLOGY(H,K,)LIMITED in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 28:1D:21 has a network interface built by IN ONE SMART TECHNOLOGY(H,K,)LIMITED.
What is the OUI 28:1D:21?: 28:1D:21 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to IN ONE SMART TECHNOLOGY(H,K,)LIMITED. It covers every address from 28:1D:21:00:00:00 to 28:1D:21:FF:FF:FF, or 16,777,216 addresses in total. It is also written 28-1D-21.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 28:1D:21:00:00:00 that is 28:1D:21 — 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 IN ONE SMART TECHNOLOGY(H,K,)LIMITED located?: IN ONE SMART TECHNOLOGY(H,K,)LIMITED is listed at UNIT I 1/F MAU LAM COMM BLDG 16-18 MAU LAM ST JORDAN KL HK HONGKONG HK 999077 in the IEEE OUI registry entry for 28:1D:21. This is the address the organization registered with the IEEE, which may differ from its current operating address.