Which company owns MAC address prefix D4:F5:27?

MAC address prefix D4:F5:27 is registered to SIEMENS AG in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with D4:F5:27 has a network interface built by SIEMENS AG.

What is the OUI D4:F5:27?

D4:F5:27 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to SIEMENS AG. It covers every address from D4:F5:27:00:00:00 to D4:F5:27:FF:FF:FF, or 16,777,216 addresses in total. It is also written D4-F5-27.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in D4:F5:27:00:00:00 that is D4:F5:27 — 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 SIEMENS AG located?

SIEMENS AG is listed at Oestliche Rheinbrückenstraße 50 Karlsruhe Baden-Württemberg DE 76181 in the IEEE OUI registry entry for D4:F5:27. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does SIEMENS AG own?

SIEMENS AG holds 7 OUI prefixes in the IEEE registry, of which D4:F5:27 is one. A device made by SIEMENS AG could carry a MAC address from any of them.

SIEMENS AG

MAC address prefix D4:F5:27 is registered to SIEMENS AG in the IEEE OUI registry. Any device whose MAC address begins with D4:F5:27 has a network interface built by SIEMENS AG. 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 D4:F5:27:00:00:00 to D4:F5:27:FF:FF:FF.

OUI prefix: D4:F5:27
Hyphen form: D4-F5-27
MAC range: D4:F5:27:00:00:00 – D4:F5:27:FF:FF:FF
Addresses in block: 16,777,216
Organization: SIEMENS AG
Address: Oestliche Rheinbrückenstraße 50 Karlsruhe Baden-Württemberg DE 76181
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 SIEMENS AG

SIEMENS AG holds 7 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.

2018-12-21Assigned to "SIEMENS AG"
archived source →
2026-07-17Assigned to "SIEMENS AG"

Nearby in the registry

The prefixes assigned immediately before and after D4:F5:27:

FAQ

Which company owns MAC address prefix D4:F5:27?: MAC address prefix D4:F5:27 is registered to SIEMENS AG in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with D4:F5:27 has a network interface built by SIEMENS AG.
What is the OUI D4:F5:27?: D4:F5:27 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to SIEMENS AG. It covers every address from D4:F5:27:00:00:00 to D4:F5:27:FF:FF:FF, or 16,777,216 addresses in total. It is also written D4-F5-27.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in D4:F5:27:00:00:00 that is D4:F5:27 — 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 SIEMENS AG located?: SIEMENS AG is listed at Oestliche Rheinbrückenstraße 50 Karlsruhe Baden-Württemberg DE 76181 in the IEEE OUI registry entry for D4:F5:27. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does SIEMENS AG own?: SIEMENS AG holds 7 OUI prefixes in the IEEE registry, of which D4:F5:27 is one. A device made by SIEMENS AG could carry a MAC address from any of them.