Which company owns MAC address prefix 34:0F:66?

MAC address prefix 34:0F:66 is registered to Web Sensing LLC in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 34:0F:66 has a network interface built by Web Sensing LLC.

What is the OUI 34:0F:66?

34:0F:66 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Web Sensing LLC. It covers every address from 34:0F:66:00:00:00 to 34:0F:66:FF:FF:FF, or 16,777,216 addresses in total. It is also written 34-0F-66.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 34:0F:66:00:00:00 that is 34:0F:66 — 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 Web Sensing LLC located?

Web Sensing LLC is listed at P.O. Box 692 Hanover NH US 03755 in the IEEE OUI registry entry for 34:0F:66. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Web Sensing LLC

MAC address prefix 34:0F:66 is registered to Web Sensing LLC in the IEEE OUI registry. Any device whose MAC address begins with 34:0F:66 has a network interface built by Web Sensing 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 34:0F:66:00:00:00 to 34:0F:66:FF:FF:FF.

OUI prefix: 34:0F:66
Hyphen form: 34-0F-66
MAC range: 34:0F:66:00:00:00 – 34:0F:66:FF:FF:FF
Addresses in block: 16,777,216
Organization: Web Sensing LLC
Address: P.O. Box 692 Hanover NH US 03755
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 (3)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2019-08-04Assigned to "MicroArx Corporation"
archived source →
2020-08-05Renamed from "MicroArx Corporation" to "Web Sensing LLC"
archived source →
2026-07-17Assigned to "Web Sensing LLC"

Nearby in the registry

The prefixes assigned immediately before and after 34:0F:66:

FAQ

Which company owns MAC address prefix 34:0F:66?: MAC address prefix 34:0F:66 is registered to Web Sensing LLC in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 34:0F:66 has a network interface built by Web Sensing LLC.
What is the OUI 34:0F:66?: 34:0F:66 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Web Sensing LLC. It covers every address from 34:0F:66:00:00:00 to 34:0F:66:FF:FF:FF, or 16,777,216 addresses in total. It is also written 34-0F-66.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 34:0F:66:00:00:00 that is 34:0F:66 — 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 Web Sensing LLC located?: Web Sensing LLC is listed at P.O. Box 692 Hanover NH US 03755 in the IEEE OUI registry entry for 34:0F:66. This is the address the organization registered with the IEEE, which may differ from its current operating address.