Which company owns MAC address prefix 7C:55:A7?

MAC address prefix 7C:55:A7 is registered to Kastle Systems in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 7C:55:A7 has a network interface built by Kastle Systems.

What is the OUI 7C:55:A7?

7C:55:A7 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Kastle Systems. It covers every address from 7C:55:A7:00:00:00 to 7C:55:A7:FF:FF:FF, or 16,777,216 addresses in total. It is also written 7C-55-A7.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 7C:55:A7:00:00:00 that is 7C:55:A7 — 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 Kastle Systems located?

Kastle Systems is listed at 6402 Arlington Blvd Falls Church VA US 22042 in the IEEE OUI registry entry for 7C:55:A7. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Kastle Systems

MAC address prefix 7C:55:A7 is registered to Kastle Systems in the IEEE OUI registry. Any device whose MAC address begins with 7C:55:A7 has a network interface built by Kastle Systems. 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 7C:55:A7:00:00:00 to 7C:55:A7:FF:FF:FF.

OUI prefix: 7C:55:A7
Hyphen form: 7C-55-A7
MAC range: 7C:55:A7:00:00:00 – 7C:55:A7:FF:FF:FF
Addresses in block: 16,777,216
Organization: Kastle Systems
Address: 6402 Arlington Blvd Falls Church VA US 22042
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.

2021-02-25Assigned to "Kastle Systems"
archived source →
2026-07-17Assigned to "Kastle Systems"

Nearby in the registry

The prefixes assigned immediately before and after 7C:55:A7:

FAQ

Which company owns MAC address prefix 7C:55:A7?: MAC address prefix 7C:55:A7 is registered to Kastle Systems in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 7C:55:A7 has a network interface built by Kastle Systems.
What is the OUI 7C:55:A7?: 7C:55:A7 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Kastle Systems. It covers every address from 7C:55:A7:00:00:00 to 7C:55:A7:FF:FF:FF, or 16,777,216 addresses in total. It is also written 7C-55-A7.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 7C:55:A7:00:00:00 that is 7C:55:A7 — 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 Kastle Systems located?: Kastle Systems is listed at 6402 Arlington Blvd Falls Church VA US 22042 in the IEEE OUI registry entry for 7C:55:A7. This is the address the organization registered with the IEEE, which may differ from its current operating address.