Which company owns MAC address prefix 3C:1A:57?

MAC address prefix 3C:1A:57 is registered to Cardiopulmonary Corp in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 3C:1A:57 has a network interface built by Cardiopulmonary Corp.

What is the OUI 3C:1A:57?

3C:1A:57 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Cardiopulmonary Corp. It covers every address from 3C:1A:57:00:00:00 to 3C:1A:57:FF:FF:FF, or 16,777,216 addresses in total. It is also written 3C-1A-57.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 3C:1A:57:00:00:00 that is 3C:1A:57 — 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 Cardiopulmonary Corp located?

Cardiopulmonary Corp is listed at 200 Cascade Blvd Milford CT US 06460 in the IEEE OUI registry entry for 3C:1A:57. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Cardiopulmonary Corp

MAC address prefix 3C:1A:57 is registered to Cardiopulmonary Corp in the IEEE OUI registry. Any device whose MAC address begins with 3C:1A:57 has a network interface built by Cardiopulmonary Corp. 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 3C:1A:57:00:00:00 to 3C:1A:57:FF:FF:FF.

OUI prefix: 3C:1A:57
Hyphen form: 3C-1A-57
MAC range: 3C:1A:57:00:00:00 – 3C:1A:57:FF:FF:FF
Addresses in block: 16,777,216
Organization: Cardiopulmonary Corp
Address: 200 Cascade Blvd Milford CT US 06460
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 "Cardiopulmonary Corp"
archived source →
2026-07-17Assigned to "Cardiopulmonary Corp"

Nearby in the registry

The prefixes assigned immediately before and after 3C:1A:57:

FAQ

Which company owns MAC address prefix 3C:1A:57?: MAC address prefix 3C:1A:57 is registered to Cardiopulmonary Corp in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 3C:1A:57 has a network interface built by Cardiopulmonary Corp.
What is the OUI 3C:1A:57?: 3C:1A:57 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Cardiopulmonary Corp. It covers every address from 3C:1A:57:00:00:00 to 3C:1A:57:FF:FF:FF, or 16,777,216 addresses in total. It is also written 3C-1A-57.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 3C:1A:57:00:00:00 that is 3C:1A:57 — 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 Cardiopulmonary Corp located?: Cardiopulmonary Corp is listed at 200 Cascade Blvd Milford CT US 06460 in the IEEE OUI registry entry for 3C:1A:57. This is the address the organization registered with the IEEE, which may differ from its current operating address.