Which company owns MAC address prefix 40:D9:5A?

MAC address prefix 40:D9:5A is registered to AMPAK Technology,Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:D9:5A has a network interface built by AMPAK Technology,Inc..

What is the OUI 40:D9:5A?

40:D9:5A is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to AMPAK Technology,Inc.. It covers every address from 40:D9:5A:00:00:00 to 40:D9:5A:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-D9-5A.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 40:D9:5A:00:00:00 that is 40:D9:5A — 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 AMPAK Technology,Inc. located?

AMPAK Technology,Inc. is listed at 3F, No.15-1 Zhonghua Road, Hsinchu Industrail Park, Hukou, Hsinchu Hsinchu,Taiwan R.O.C. TW 30352 in the IEEE OUI registry entry for 40:D9:5A. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does AMPAK Technology,Inc. own?

AMPAK Technology,Inc. holds 19 OUI prefixes in the IEEE registry, of which 40:D9:5A is one. A device made by AMPAK Technology,Inc. could carry a MAC address from any of them.

AMPAK Technology,Inc.

MAC address prefix 40:D9:5A is registered to AMPAK Technology,Inc. in the IEEE OUI registry. Any device whose MAC address begins with 40:D9:5A has a network interface built by AMPAK Technology,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 40:D9:5A:00:00:00 to 40:D9:5A:FF:FF:FF.

OUI prefix: 40:D9:5A
Hyphen form: 40-D9-5A
MAC range: 40:D9:5A:00:00:00 – 40:D9:5A:FF:FF:FF
Addresses in block: 16,777,216
Organization: AMPAK Technology,Inc.
Address: 3F, No.15-1 Zhonghua Road, Hsinchu Industrail Park, Hukou, Hsinchu Hsinchu,Taiwan R.O.C. TW 30352
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 AMPAK Technology,Inc.

AMPAK Technology,Inc. holds 19 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2022-07-11Assigned to "AMPAK Technology,Inc."
archived source →
2026-07-17Assigned to "AMPAK Technology,Inc."

Nearby in the registry

The prefixes assigned immediately before and after 40:D9:5A:

FAQ

Which company owns MAC address prefix 40:D9:5A?: MAC address prefix 40:D9:5A is registered to AMPAK Technology,Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:D9:5A has a network interface built by AMPAK Technology,Inc..
What is the OUI 40:D9:5A?: 40:D9:5A is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to AMPAK Technology,Inc.. It covers every address from 40:D9:5A:00:00:00 to 40:D9:5A:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-D9-5A.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 40:D9:5A:00:00:00 that is 40:D9:5A — 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 AMPAK Technology,Inc. located?: AMPAK Technology,Inc. is listed at 3F, No.15-1 Zhonghua Road, Hsinchu Industrail Park, Hukou, Hsinchu Hsinchu,Taiwan R.O.C. TW 30352 in the IEEE OUI registry entry for 40:D9:5A. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does AMPAK Technology,Inc. own?: AMPAK Technology,Inc. holds 19 OUI prefixes in the IEEE registry, of which 40:D9:5A is one. A device made by AMPAK Technology,Inc. could carry a MAC address from any of them.