Which company owns MAC address prefix AC:A9:19?

MAC address prefix AC:A9:19 is registered to TrekStor GmbH in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with AC:A9:19 has a network interface built by TrekStor GmbH.

What is the OUI AC:A9:19?

AC:A9:19 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TrekStor GmbH. It covers every address from AC:A9:19:00:00:00 to AC:A9:19:FF:FF:FF, or 16,777,216 addresses in total. It is also written AC-A9-19.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in AC:A9:19:00:00:00 that is AC:A9:19 — 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 TrekStor GmbH located?

TrekStor GmbH is listed at Kastanienallee 8-10 Lorsch Hessen DE 64653 in the IEEE OUI registry entry for AC:A9:19. This is the address the organization registered with the IEEE, which may differ from its current operating address.

TrekStor GmbH

MAC address prefix AC:A9:19 is registered to TrekStor GmbH in the IEEE OUI registry. Any device whose MAC address begins with AC:A9:19 has a network interface built by TrekStor GmbH. 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:A9:19:00:00:00 to AC:A9:19:FF:FF:FF.

OUI prefix: AC:A9:19
Hyphen form: AC-A9-19
MAC range: AC:A9:19:00:00:00 – AC:A9:19:FF:FF:FF
Addresses in block: 16,777,216
Organization: TrekStor GmbH
Address: Kastanienallee 8-10 Lorsch Hessen DE 64653
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.

2016-07-29Assigned to "TrekStor GmbH"
archived source →
2026-07-17Assigned to "TrekStor GmbH"

Nearby in the registry

The prefixes assigned immediately before and after AC:A9:19:

FAQ

Which company owns MAC address prefix AC:A9:19?: MAC address prefix AC:A9:19 is registered to TrekStor GmbH in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with AC:A9:19 has a network interface built by TrekStor GmbH.
What is the OUI AC:A9:19?: AC:A9:19 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TrekStor GmbH. It covers every address from AC:A9:19:00:00:00 to AC:A9:19:FF:FF:FF, or 16,777,216 addresses in total. It is also written AC-A9-19.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in AC:A9:19:00:00:00 that is AC:A9:19 — 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 TrekStor GmbH located?: TrekStor GmbH is listed at Kastanienallee 8-10 Lorsch Hessen DE 64653 in the IEEE OUI registry entry for AC:A9:19. This is the address the organization registered with the IEEE, which may differ from its current operating address.