Which company owns MAC address prefix FC:4A:E9?

MAC address prefix FC:4A:E9 is registered to Castlenet Technology Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with FC:4A:E9 has a network interface built by Castlenet Technology Inc..

What is the OUI FC:4A:E9?

FC:4A:E9 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Castlenet Technology Inc.. It covers every address from FC:4A:E9:00:00:00 to FC:4A:E9:FF:FF:FF, or 16,777,216 addresses in total. It is also written FC-4A-E9.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in FC:4A:E9:00:00:00 that is FC:4A:E9 — 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 Castlenet Technology Inc. located?

Castlenet Technology Inc. is listed at 5F., No. 10, Daye Rd., Beitou Dist. Taipei City TW 112030 in the IEEE OUI registry entry for FC:4A:E9. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Castlenet Technology Inc. own?

Castlenet Technology Inc. holds 5 OUI prefixes in the IEEE registry, of which FC:4A:E9 is one. A device made by Castlenet Technology Inc. could carry a MAC address from any of them.

Castlenet Technology Inc.

MAC address prefix FC:4A:E9 is registered to Castlenet Technology Inc. in the IEEE OUI registry. Any device whose MAC address begins with FC:4A:E9 has a network interface built by Castlenet Technology 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 FC:4A:E9:00:00:00 to FC:4A:E9:FF:FF:FF.

OUI prefix: FC:4A:E9
Hyphen form: FC-4A-E9
MAC range: FC:4A:E9:00:00:00 – FC:4A:E9:FF:FF:FF
Addresses in block: 16,777,216
Organization: Castlenet Technology Inc.
Address: 5F., No. 10, Daye Rd., Beitou Dist. Taipei City TW 112030
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 Castlenet Technology Inc.

Castlenet Technology Inc. holds 5 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.

2016-07-29Assigned to "Castlenet Technology Inc."
archived source →
2026-07-17Assigned to "Castlenet Technology Inc."

Nearby in the registry

The prefixes assigned immediately before and after FC:4A:E9:

FAQ

Which company owns MAC address prefix FC:4A:E9?: MAC address prefix FC:4A:E9 is registered to Castlenet Technology Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with FC:4A:E9 has a network interface built by Castlenet Technology Inc..
What is the OUI FC:4A:E9?: FC:4A:E9 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Castlenet Technology Inc.. It covers every address from FC:4A:E9:00:00:00 to FC:4A:E9:FF:FF:FF, or 16,777,216 addresses in total. It is also written FC-4A-E9.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in FC:4A:E9:00:00:00 that is FC:4A:E9 — 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 Castlenet Technology Inc. located?: Castlenet Technology Inc. is listed at 5F., No. 10, Daye Rd., Beitou Dist. Taipei City TW 112030 in the IEEE OUI registry entry for FC:4A:E9. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Castlenet Technology Inc. own?: Castlenet Technology Inc. holds 5 OUI prefixes in the IEEE registry, of which FC:4A:E9 is one. A device made by Castlenet Technology Inc. could carry a MAC address from any of them.