Which company owns MAC address prefix AC:51:EE?

MAC address prefix AC:51:EE is registered to Adtran Inc in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with AC:51:EE has a network interface built by Adtran Inc.

What is the OUI AC:51:EE?

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

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in AC:51:EE:00:00:00 that is AC:51:EE — 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 Adtran Inc located?

Adtran Inc is listed at Sheraton House Cambridge Cambridgeshire GB CB3 0AX in the IEEE OUI registry entry for AC:51:EE. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Adtran Inc own?

Adtran Inc holds 15 OUI prefixes in the IEEE registry, of which AC:51:EE is one. A device made by Adtran Inc could carry a MAC address from any of them.

Adtran Inc

MAC address prefix AC:51:EE is registered to Adtran Inc in the IEEE OUI registry. Any device whose MAC address begins with AC:51:EE has a network interface built by Adtran 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 AC:51:EE:00:00:00 to AC:51:EE:FF:FF:FF.

OUI prefix: AC:51:EE
Hyphen form: AC-51-EE
MAC range: AC:51:EE:00:00:00 – AC:51:EE:FF:FF:FF
Addresses in block: 16,777,216
Organization: Adtran Inc
Address: Sheraton House Cambridge Cambridgeshire GB CB3 0AX
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.

Other prefixes from Adtran Inc

Adtran Inc holds 15 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (3)

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 "Cambridge Communication Systems Ltd"
archived source →
2023-07-11Renamed from "Cambridge Communication Systems Ltd" to "Adtran Inc"
archived source →
2026-07-17Assigned to "Adtran Inc"

Nearby in the registry

The prefixes assigned immediately before and after AC:51:EE:

FAQ

Which company owns MAC address prefix AC:51:EE?: MAC address prefix AC:51:EE is registered to Adtran Inc in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with AC:51:EE has a network interface built by Adtran Inc.
What is the OUI AC:51:EE?: AC:51:EE is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Adtran Inc. It covers every address from AC:51:EE:00:00:00 to AC:51:EE:FF:FF:FF, or 16,777,216 addresses in total. It is also written AC-51-EE.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in AC:51:EE:00:00:00 that is AC:51:EE — 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 Adtran Inc located?: Adtran Inc is listed at Sheraton House Cambridge Cambridgeshire GB CB3 0AX in the IEEE OUI registry entry for AC:51:EE. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Adtran Inc own?: Adtran Inc holds 15 OUI prefixes in the IEEE registry, of which AC:51:EE is one. A device made by Adtran Inc could carry a MAC address from any of them.