Which company owns MAC address prefix C4:19:EC?

MAC address prefix C4:19:EC is registered to Qualisys AB in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with C4:19:EC has a network interface built by Qualisys AB.

What is the OUI C4:19:EC?

C4:19:EC is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Qualisys AB. It covers every address from C4:19:EC:00:00:00 to C4:19:EC:FF:FF:FF, or 16,777,216 addresses in total. It is also written C4-19-EC.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in C4:19:EC:00:00:00 that is C4:19:EC — 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 Qualisys AB located?

Qualisys AB is listed at Packhusgatan 6 Gothenburg SE 41113 in the IEEE OUI registry entry for C4:19:EC. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Qualisys AB

MAC address prefix C4:19:EC is registered to Qualisys AB in the IEEE OUI registry. Any device whose MAC address begins with C4:19:EC has a network interface built by Qualisys AB. 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 C4:19:EC:00:00:00 to C4:19:EC:FF:FF:FF.

OUI prefix: C4:19:EC
Hyphen form: C4-19-EC
MAC range: C4:19:EC:00:00:00 – C4:19:EC:FF:FF:FF
Addresses in block: 16,777,216
Organization: Qualisys AB
Address: Packhusgatan 6 Gothenburg SE 41113
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 "Qualisys AB"
archived source →
2026-07-17Assigned to "Qualisys AB"

Nearby in the registry

The prefixes assigned immediately before and after C4:19:EC:

FAQ

Which company owns MAC address prefix C4:19:EC?: MAC address prefix C4:19:EC is registered to Qualisys AB in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with C4:19:EC has a network interface built by Qualisys AB.
What is the OUI C4:19:EC?: C4:19:EC is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Qualisys AB. It covers every address from C4:19:EC:00:00:00 to C4:19:EC:FF:FF:FF, or 16,777,216 addresses in total. It is also written C4-19-EC.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in C4:19:EC:00:00:00 that is C4:19:EC — 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 Qualisys AB located?: Qualisys AB is listed at Packhusgatan 6 Gothenburg SE 41113 in the IEEE OUI registry entry for C4:19:EC. This is the address the organization registered with the IEEE, which may differ from its current operating address.