Which company owns MAC address prefix 5C:FF:FF?

MAC address prefix 5C:FF:FF is registered to Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 5C:FF:FF has a network interface built by Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 5C:FF:FF:00:00:00 that is 5C:FF:FF — 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.

Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd

MAC address prefix 5C:FF:FF is registered to Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd in the IEEE OUI registry. Any device whose MAC address begins with 5C:FF:FF has a network interface built by Shenzhen Kezhonglong Optoelectronic Technology Co., 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 5C:FF:FF:00:00:00 to 5C:FF:FF:FF:FF:FF.

OUI prefix: 5C:FF:FF
Hyphen form: 5C-FF-FF
MAC range: 5C:FF:FF:00:00:00 – 5C:FF:FF:FF:FF:FF
Addresses in block: 16,777,216
Organization: Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd
Address: 3/F, B5 Building, Xinfu Industrial Park, Heping Village Shenzhen, Guangdong 518101 US
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.

2016-07-29Assigned to "Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd"
archived source →
2026-07-17Assigned to "Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd"

Nearby in the registry

The prefixes assigned immediately before and after 5C:FF:FF:

FAQ

Which company owns MAC address prefix 5C:FF:FF?: MAC address prefix 5C:FF:FF is registered to Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 5C:FF:FF has a network interface built by Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd.
What is the OUI 5C:FF:FF?: 5C:FF:FF is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd. It covers every address from 5C:FF:FF:00:00:00 to 5C:FF:FF:FF:FF:FF, or 16,777,216 addresses in total. It is also written 5C-FF-FF.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 5C:FF:FF:00:00:00 that is 5C:FF:FF — 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 Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd located?: Shenzhen Kezhonglong Optoelectronic Technology Co., Ltd is listed at 3/F, B5 Building, Xinfu Industrial Park, Heping Village Shenzhen, Guangdong 518101 US in the IEEE OUI registry entry for 5C:FF:FF. This is the address the organization registered with the IEEE, which may differ from its current operating address.