Which company owns MAC address prefix 38:33:C5?

MAC address prefix 38:33:C5 is registered to Microsoft Corporation in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 38:33:C5 has a network interface built by Microsoft Corporation.

What is the OUI 38:33:C5?

38:33:C5 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Microsoft Corporation. It covers every address from 38:33:C5:00:00:00 to 38:33:C5:FF:FF:FF, or 16,777,216 addresses in total. It is also written 38-33-C5.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 38:33:C5:00:00:00 that is 38:33:C5 — 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 Microsoft Corporation located?

Microsoft Corporation is listed at One Microsoft Way REDMOND WA US 98052 in the IEEE OUI registry entry for 38:33:C5. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Microsoft Corporation own?

Microsoft Corporation holds 105 OUI prefixes in the IEEE registry, of which 38:33:C5 is one. A device made by Microsoft Corporation could carry a MAC address from any of them.

Microsoft Corporation

MAC address prefix 38:33:C5 is registered to Microsoft Corporation in the IEEE OUI registry. Any device whose MAC address begins with 38:33:C5 has a network interface built by Microsoft Corporation. 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 38:33:C5:00:00:00 to 38:33:C5:FF:FF:FF.

OUI prefix: 38:33:C5
Hyphen form: 38-33-C5
MAC range: 38:33:C5:00:00:00 – 38:33:C5:FF:FF:FF
Addresses in block: 16,777,216
Organization: Microsoft Corporation
Address: One Microsoft Way REDMOND WA US 98052
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.

Other prefixes from Microsoft Corporation

Microsoft Corporation holds 105 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

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

2026-01-08Assigned to "Microsoft Corporation"
archived source →
2026-07-17Assigned to "Microsoft Corporation"

Nearby in the registry

The prefixes assigned immediately before and after 38:33:C5:

FAQ

Which company owns MAC address prefix 38:33:C5?: MAC address prefix 38:33:C5 is registered to Microsoft Corporation in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 38:33:C5 has a network interface built by Microsoft Corporation.
What is the OUI 38:33:C5?: 38:33:C5 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Microsoft Corporation. It covers every address from 38:33:C5:00:00:00 to 38:33:C5:FF:FF:FF, or 16,777,216 addresses in total. It is also written 38-33-C5.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 38:33:C5:00:00:00 that is 38:33:C5 — 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 Microsoft Corporation located?: Microsoft Corporation is listed at One Microsoft Way REDMOND WA US 98052 in the IEEE OUI registry entry for 38:33:C5. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Microsoft Corporation own?: Microsoft Corporation holds 105 OUI prefixes in the IEEE registry, of which 38:33:C5 is one. A device made by Microsoft Corporation could carry a MAC address from any of them.