Which company owns MAC address prefix 00:1F:39?

MAC address prefix 00:1F:39 is registered to Construcciones y Auxiliar de Ferrocarriles, S.A. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:1F:39 has a network interface built by Construcciones y Auxiliar de Ferrocarriles, S.A..

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 00:1F:39:00:00:00 that is 00:1F:39 — 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.

Construcciones y Auxiliar de Ferrocarriles, S.A.

MAC address prefix 00:1F:39 is registered to Construcciones y Auxiliar de Ferrocarriles, S.A. in the IEEE OUI registry. Any device whose MAC address begins with 00:1F:39 has a network interface built by Construcciones y Auxiliar de Ferrocarriles, S.A.. 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 00:1F:39:00:00:00 to 00:1F:39:FF:FF:FF.

OUI prefix: 00:1F:39
Hyphen form: 00-1F-39
MAC range: 00:1F:39:00:00:00 – 00:1F:39:FF:FF:FF
Addresses in block: 16,777,216
Organization: Construcciones y Auxiliar de Ferrocarriles, S.A.
Address: C/ J.M. Iturrioz, 26 Beasain Guipúzcoa ES E-20200
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 "Construcciones y Auxiliar de Ferrocarriles, S.A."
archived source →
2026-07-17Assigned to "Construcciones y Auxiliar de Ferrocarriles, S.A."

Nearby in the registry

The prefixes assigned immediately before and after 00:1F:39:

FAQ

Which company owns MAC address prefix 00:1F:39?: MAC address prefix 00:1F:39 is registered to Construcciones y Auxiliar de Ferrocarriles, S.A. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:1F:39 has a network interface built by Construcciones y Auxiliar de Ferrocarriles, S.A..
What is the OUI 00:1F:39?: 00:1F:39 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Construcciones y Auxiliar de Ferrocarriles, S.A.. It covers every address from 00:1F:39:00:00:00 to 00:1F:39:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-1F-39.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 00:1F:39:00:00:00 that is 00:1F:39 — 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 Construcciones y Auxiliar de Ferrocarriles, S.A. located?: Construcciones y Auxiliar de Ferrocarriles, S.A. is listed at C/ J.M. Iturrioz, 26 Beasain Guipúzcoa ES E-20200 in the IEEE OUI registry entry for 00:1F:39. This is the address the organization registered with the IEEE, which may differ from its current operating address.