Which company owns MAC address prefix 7C:A1:5D?

MAC address prefix 7C:A1:5D is registered to GN ReSound A/S in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 7C:A1:5D has a network interface built by GN ReSound A/S.

What is the OUI 7C:A1:5D?

7C:A1:5D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to GN ReSound A/S. It covers every address from 7C:A1:5D:00:00:00 to 7C:A1:5D:FF:FF:FF, or 16,777,216 addresses in total. It is also written 7C-A1-5D.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 7C:A1:5D:00:00:00 that is 7C:A1:5D — 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 GN ReSound A/S located?

GN ReSound A/S is listed at Lautrupbjerg 7 Ballerup DK-CPH DK 2750 in the IEEE OUI registry entry for 7C:A1:5D. This is the address the organization registered with the IEEE, which may differ from its current operating address.

GN ReSound A/S

MAC address prefix 7C:A1:5D is registered to GN ReSound A/S in the IEEE OUI registry. Any device whose MAC address begins with 7C:A1:5D has a network interface built by GN ReSound A/S. 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 7C:A1:5D:00:00:00 to 7C:A1:5D:FF:FF:FF.

OUI prefix: 7C:A1:5D
Hyphen form: 7C-A1-5D
MAC range: 7C:A1:5D:00:00:00 – 7C:A1:5D:FF:FF:FF
Addresses in block: 16,777,216
Organization: GN ReSound A/S
Address: Lautrupbjerg 7 Ballerup DK-CPH DK 2750
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 "GN ReSound A/S"
archived source →
2026-07-17Assigned to "GN ReSound A/S"

Nearby in the registry

The prefixes assigned immediately before and after 7C:A1:5D:

FAQ

Which company owns MAC address prefix 7C:A1:5D?: MAC address prefix 7C:A1:5D is registered to GN ReSound A/S in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 7C:A1:5D has a network interface built by GN ReSound A/S.
What is the OUI 7C:A1:5D?: 7C:A1:5D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to GN ReSound A/S. It covers every address from 7C:A1:5D:00:00:00 to 7C:A1:5D:FF:FF:FF, or 16,777,216 addresses in total. It is also written 7C-A1-5D.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 7C:A1:5D:00:00:00 that is 7C:A1:5D — 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 GN ReSound A/S located?: GN ReSound A/S is listed at Lautrupbjerg 7 Ballerup DK-CPH DK 2750 in the IEEE OUI registry entry for 7C:A1:5D. This is the address the organization registered with the IEEE, which may differ from its current operating address.