Which company owns MAC address prefix 54:EF:5B?

MAC address prefix 54:EF:5B is registered to Science Corporation in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 54:EF:5B has a network interface built by Science Corporation.

What is the OUI 54:EF:5B?

54:EF:5B is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Science Corporation. It covers every address from 54:EF:5B:00:00:00 to 54:EF:5B:FF:FF:FF, or 16,777,216 addresses in total. It is also written 54-EF-5B.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 54:EF:5B:00:00:00 that is 54:EF:5B — 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 Science Corporation located?

Science Corporation is listed at 300 Wind River Way Alameda CA US 94501 in the IEEE OUI registry entry for 54:EF:5B. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Science Corporation

MAC address prefix 54:EF:5B is registered to Science Corporation in the IEEE OUI registry. Any device whose MAC address begins with 54:EF:5B has a network interface built by Science Corporation. 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 54:EF:5B:00:00:00 to 54:EF:5B:FF:FF:FF.

OUI prefix: 54:EF:5B
Hyphen form: 54-EF-5B
MAC range: 54:EF:5B:00:00:00 – 54:EF:5B:FF:FF:FF
Addresses in block: 16,777,216
Organization: Science Corporation
Address: 300 Wind River Way Alameda CA US 94501
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 "Science Corporation"
archived source →
2026-07-17Assigned to "Science Corporation"

Nearby in the registry

The prefixes assigned immediately before and after 54:EF:5B:

FAQ

Which company owns MAC address prefix 54:EF:5B?: MAC address prefix 54:EF:5B is registered to Science Corporation in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 54:EF:5B has a network interface built by Science Corporation.
What is the OUI 54:EF:5B?: 54:EF:5B is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Science Corporation. It covers every address from 54:EF:5B:00:00:00 to 54:EF:5B:FF:FF:FF, or 16,777,216 addresses in total. It is also written 54-EF-5B.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 54:EF:5B:00:00:00 that is 54:EF:5B — 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 Science Corporation located?: Science Corporation is listed at 300 Wind River Way Alameda CA US 94501 in the IEEE OUI registry entry for 54:EF:5B. This is the address the organization registered with the IEEE, which may differ from its current operating address.