Which company owns MAC address prefix A4:5E:5A?

MAC address prefix A4:5E:5A is registered to ACTIVIO Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:5E:5A has a network interface built by ACTIVIO Inc..

What is the OUI A4:5E:5A?

A4:5E:5A is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to ACTIVIO Inc.. It covers every address from A4:5E:5A:00:00:00 to A4:5E:5A:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-5E-5A.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in A4:5E:5A:00:00:00 that is A4:5E:5A — 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 ACTIVIO Inc. located?

ACTIVIO Inc. is listed at Takeuchi Lorie Bldg. Room 503, 1-34-12, Takadanobaba Shinjuku-ku Tokyo JP 1690075 in the IEEE OUI registry entry for A4:5E:5A. This is the address the organization registered with the IEEE, which may differ from its current operating address.

ACTIVIO Inc.

MAC address prefix A4:5E:5A is registered to ACTIVIO Inc. in the IEEE OUI registry. Any device whose MAC address begins with A4:5E:5A has a network interface built by ACTIVIO 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 A4:5E:5A:00:00:00 to A4:5E:5A:FF:FF:FF.

OUI prefix: A4:5E:5A
Hyphen form: A4-5E-5A
MAC range: A4:5E:5A:00:00:00 – A4:5E:5A:FF:FF:FF
Addresses in block: 16,777,216
Organization: ACTIVIO Inc.
Address: Takeuchi Lorie Bldg. Room 503, 1-34-12, Takadanobaba Shinjuku-ku Tokyo JP 1690075
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.

2020-11-28Assigned to "ACTIVIO Inc."
archived source →
2026-07-17Assigned to "ACTIVIO Inc."

Nearby in the registry

The prefixes assigned immediately before and after A4:5E:5A:

FAQ

Which company owns MAC address prefix A4:5E:5A?: MAC address prefix A4:5E:5A is registered to ACTIVIO Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:5E:5A has a network interface built by ACTIVIO Inc..
What is the OUI A4:5E:5A?: A4:5E:5A is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to ACTIVIO Inc.. It covers every address from A4:5E:5A:00:00:00 to A4:5E:5A:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-5E-5A.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in A4:5E:5A:00:00:00 that is A4:5E:5A — 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 ACTIVIO Inc. located?: ACTIVIO Inc. is listed at Takeuchi Lorie Bldg. Room 503, 1-34-12, Takadanobaba Shinjuku-ku Tokyo JP 1690075 in the IEEE OUI registry entry for A4:5E:5A. This is the address the organization registered with the IEEE, which may differ from its current operating address.