Which company owns MAC address prefix 38:AC:3D?

MAC address prefix 38:AC:3D is registered to Nephos Inc in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 38:AC:3D has a network interface built by Nephos Inc.

What is the OUI 38:AC:3D?

38:AC:3D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Nephos Inc. It covers every address from 38:AC:3D:00:00:00 to 38:AC:3D:FF:FF:FF, or 16,777,216 addresses in total. It is also written 38-AC-3D.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 38:AC:3D:00:00:00 that is 38:AC:3D — 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 Nephos Inc located?

Nephos Inc is listed at 2840 Junction Ave. , San Jose CA US 95134 in the IEEE OUI registry entry for 38:AC:3D. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Nephos Inc

MAC address prefix 38:AC:3D is registered to Nephos Inc in the IEEE OUI registry. Any device whose MAC address begins with 38:AC:3D has a network interface built by Nephos Inc. 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 38:AC:3D:00:00:00 to 38:AC:3D:FF:FF:FF.

OUI prefix: 38:AC:3D
Hyphen form: 38-AC-3D
MAC range: 38:AC:3D:00:00:00 – 38:AC:3D:FF:FF:FF
Addresses in block: 16,777,216
Organization: Nephos Inc
Address: 2840 Junction Ave. , San Jose CA US 95134
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.

2017-09-08Assigned to "Nephos Inc"
archived source →
2026-07-17Assigned to "Nephos Inc"

Nearby in the registry

The prefixes assigned immediately before and after 38:AC:3D:

FAQ

Which company owns MAC address prefix 38:AC:3D?: MAC address prefix 38:AC:3D is registered to Nephos Inc in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 38:AC:3D has a network interface built by Nephos Inc.
What is the OUI 38:AC:3D?: 38:AC:3D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Nephos Inc. It covers every address from 38:AC:3D:00:00:00 to 38:AC:3D:FF:FF:FF, or 16,777,216 addresses in total. It is also written 38-AC-3D.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 38:AC:3D:00:00:00 that is 38:AC:3D — 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 Nephos Inc located?: Nephos Inc is listed at 2840 Junction Ave. , San Jose CA US 95134 in the IEEE OUI registry entry for 38:AC:3D. This is the address the organization registered with the IEEE, which may differ from its current operating address.