Which company owns MAC address prefix 04:C9:91?

MAC address prefix 04:C9:91 is registered to Phistek INC. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 04:C9:91 has a network interface built by Phistek INC..

What is the OUI 04:C9:91?

04:C9:91 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Phistek INC.. It covers every address from 04:C9:91:00:00:00 to 04:C9:91:FF:FF:FF, or 16,777,216 addresses in total. It is also written 04-C9-91.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 04:C9:91:00:00:00 that is 04:C9:91 — 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 Phistek INC. located?

Phistek INC. is listed at 5 Floor, No.188, Section 3, Datong Road New Taipei City TW 221 in the IEEE OUI registry entry for 04:C9:91. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Phistek INC.

MAC address prefix 04:C9:91 is registered to Phistek INC. in the IEEE OUI registry. Any device whose MAC address begins with 04:C9:91 has a network interface built by Phistek 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 04:C9:91:00:00:00 to 04:C9:91:FF:FF:FF.

OUI prefix: 04:C9:91
Hyphen form: 04-C9-91
MAC range: 04:C9:91:00:00:00 – 04:C9:91:FF:FF:FF
Addresses in block: 16,777,216
Organization: Phistek INC.
Address: 5 Floor, No.188, Section 3, Datong Road New Taipei City TW 221
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 "Phistek INC."
archived source →
2026-07-17Assigned to "Phistek INC."

Nearby in the registry

The prefixes assigned immediately before and after 04:C9:91:

FAQ

Which company owns MAC address prefix 04:C9:91?: MAC address prefix 04:C9:91 is registered to Phistek INC. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 04:C9:91 has a network interface built by Phistek INC..
What is the OUI 04:C9:91?: 04:C9:91 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Phistek INC.. It covers every address from 04:C9:91:00:00:00 to 04:C9:91:FF:FF:FF, or 16,777,216 addresses in total. It is also written 04-C9-91.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 04:C9:91:00:00:00 that is 04:C9:91 — 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 Phistek INC. located?: Phistek INC. is listed at 5 Floor, No.188, Section 3, Datong Road New Taipei City TW 221 in the IEEE OUI registry entry for 04:C9:91. This is the address the organization registered with the IEEE, which may differ from its current operating address.