Which company owns MAC address prefix F4:1E:5E?

MAC address prefix F4:1E:5E is registered to RtBrick Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with F4:1E:5E has a network interface built by RtBrick Inc..

What is the OUI F4:1E:5E?

F4:1E:5E is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to RtBrick Inc.. It covers every address from F4:1E:5E:00:00:00 to F4:1E:5E:FF:FF:FF, or 16,777,216 addresses in total. It is also written F4-1E-5E.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in F4:1E:5E:00:00:00 that is F4:1E:5E — 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 RtBrick Inc. located?

RtBrick Inc. is listed at 26 Kingston Terrace Princeton NJ US 08540 in the IEEE OUI registry entry for F4:1E:5E. This is the address the organization registered with the IEEE, which may differ from its current operating address.

RtBrick Inc.

MAC address prefix F4:1E:5E is registered to RtBrick Inc. in the IEEE OUI registry. Any device whose MAC address begins with F4:1E:5E has a network interface built by RtBrick Inc.. 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 F4:1E:5E:00:00:00 to F4:1E:5E:FF:FF:FF.

OUI prefix: F4:1E:5E
Hyphen form: F4-1E-5E
MAC range: F4:1E:5E:00:00:00 – F4:1E:5E:FF:FF:FF
Addresses in block: 16,777,216
Organization: RtBrick Inc.
Address: 26 Kingston Terrace Princeton NJ US 08540
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.

2017-09-08Assigned to "RtBrick Inc."
archived source →
2026-07-17Assigned to "RtBrick Inc."

Nearby in the registry

The prefixes assigned immediately before and after F4:1E:5E:

FAQ

Which company owns MAC address prefix F4:1E:5E?: MAC address prefix F4:1E:5E is registered to RtBrick Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with F4:1E:5E has a network interface built by RtBrick Inc..
What is the OUI F4:1E:5E?: F4:1E:5E is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to RtBrick Inc.. It covers every address from F4:1E:5E:00:00:00 to F4:1E:5E:FF:FF:FF, or 16,777,216 addresses in total. It is also written F4-1E-5E.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in F4:1E:5E:00:00:00 that is F4:1E:5E — 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 RtBrick Inc. located?: RtBrick Inc. is listed at 26 Kingston Terrace Princeton NJ US 08540 in the IEEE OUI registry entry for F4:1E:5E. This is the address the organization registered with the IEEE, which may differ from its current operating address.