Which company owns MAC address prefix AC:81:B5?

MAC address prefix AC:81:B5 is registered to Accton Technology Corporation in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with AC:81:B5 has a network interface built by Accton Technology Corporation.

What is the OUI AC:81:B5?

AC:81:B5 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Accton Technology Corporation. It covers every address from AC:81:B5:00:00:00 to AC:81:B5:FF:FF:FF, or 16,777,216 addresses in total. It is also written AC-81-B5.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in AC:81:B5:00:00:00 that is AC:81:B5 — 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 Accton Technology Corporation located?

Accton Technology Corporation is listed at No. 1 Creation Rd. III, Science-based Industrial Park Hsinchu TW 300 in the IEEE OUI registry entry for AC:81:B5. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Accton Technology Corporation

MAC address prefix AC:81:B5 is registered to Accton Technology Corporation in the IEEE OUI registry. Any device whose MAC address begins with AC:81:B5 has a network interface built by Accton Technology 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 AC:81:B5:00:00:00 to AC:81:B5:FF:FF:FF.

OUI prefix: AC:81:B5
Hyphen form: AC-81-B5
MAC range: AC:81:B5:00:00:00 – AC:81:B5:FF:FF:FF
Addresses in block: 16,777,216
Organization: Accton Technology Corporation
Address: No. 1 Creation Rd. III, Science-based Industrial Park Hsinchu TW 300
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.

2024-02-15Assigned to "Accton Technology Corporation"
archived source →
2026-07-17Assigned to "Accton Technology Corporation"

Nearby in the registry

The prefixes assigned immediately before and after AC:81:B5:

FAQ

Which company owns MAC address prefix AC:81:B5?: MAC address prefix AC:81:B5 is registered to Accton Technology Corporation in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with AC:81:B5 has a network interface built by Accton Technology Corporation.
What is the OUI AC:81:B5?: AC:81:B5 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Accton Technology Corporation. It covers every address from AC:81:B5:00:00:00 to AC:81:B5:FF:FF:FF, or 16,777,216 addresses in total. It is also written AC-81-B5.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in AC:81:B5:00:00:00 that is AC:81:B5 — 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 Accton Technology Corporation located?: Accton Technology Corporation is listed at No. 1 Creation Rd. III, Science-based Industrial Park Hsinchu TW 300 in the IEEE OUI registry entry for AC:81:B5. This is the address the organization registered with the IEEE, which may differ from its current operating address.