Which company owns MAC address prefix 04:21:4C?

MAC address prefix 04:21:4C is registered to Insight Energy Ventures LLC in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 04:21:4C has a network interface built by Insight Energy Ventures LLC.

What is the OUI 04:21:4C?

04:21:4C is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Insight Energy Ventures LLC. It covers every address from 04:21:4C:00:00:00 to 04:21:4C:FF:FF:FF, or 16,777,216 addresses in total. It is also written 04-21-4C.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 04:21:4C:00:00:00 that is 04:21:4C — 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 Insight Energy Ventures LLC located?

Insight Energy Ventures LLC is listed at 123 W. Fifth St Royal Oak MI US 48067 in the IEEE OUI registry entry for 04:21:4C. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Insight Energy Ventures LLC

MAC address prefix 04:21:4C is registered to Insight Energy Ventures LLC in the IEEE OUI registry. Any device whose MAC address begins with 04:21:4C has a network interface built by Insight Energy Ventures LLC. 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 04:21:4C:00:00:00 to 04:21:4C:FF:FF:FF.

OUI prefix: 04:21:4C
Hyphen form: 04-21-4C
MAC range: 04:21:4C:00:00:00 – 04:21:4C:FF:FF:FF
Addresses in block: 16,777,216
Organization: Insight Energy Ventures LLC
Address: 123 W. Fifth St Royal Oak MI US 48067
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 "Insight Energy Ventures LLC"
archived source →
2026-07-17Assigned to "Insight Energy Ventures LLC"

Nearby in the registry

The prefixes assigned immediately before and after 04:21:4C:

FAQ

Which company owns MAC address prefix 04:21:4C?: MAC address prefix 04:21:4C is registered to Insight Energy Ventures LLC in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 04:21:4C has a network interface built by Insight Energy Ventures LLC.
What is the OUI 04:21:4C?: 04:21:4C is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Insight Energy Ventures LLC. It covers every address from 04:21:4C:00:00:00 to 04:21:4C:FF:FF:FF, or 16,777,216 addresses in total. It is also written 04-21-4C.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 04:21:4C:00:00:00 that is 04:21:4C — 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 Insight Energy Ventures LLC located?: Insight Energy Ventures LLC is listed at 123 W. Fifth St Royal Oak MI US 48067 in the IEEE OUI registry entry for 04:21:4C. This is the address the organization registered with the IEEE, which may differ from its current operating address.