Which company owns MAC address prefix A4:81:7A?

MAC address prefix A4:81:7A is registered to CIG SHANGHAI CO LTD in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:81:7A has a network interface built by CIG SHANGHAI CO LTD.

What is the OUI A4:81:7A?

A4:81:7A is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to CIG SHANGHAI CO LTD. It covers every address from A4:81:7A:00:00:00 to A4:81:7A:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-81-7A.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in A4:81:7A:00:00:00 that is A4:81:7A — 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 CIG SHANGHAI CO LTD located?

CIG SHANGHAI CO LTD is listed at 5th Floor, Building 8 No 2388 Chenhang Road SHANGHAI CN 201114 in the IEEE OUI registry entry for A4:81:7A. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does CIG SHANGHAI CO LTD own?

CIG SHANGHAI CO LTD holds 25 OUI prefixes in the IEEE registry, of which A4:81:7A is one. A device made by CIG SHANGHAI CO LTD could carry a MAC address from any of them.

CIG SHANGHAI CO LTD

MAC address prefix A4:81:7A is registered to CIG SHANGHAI CO LTD in the IEEE OUI registry. Any device whose MAC address begins with A4:81:7A has a network interface built by CIG SHANGHAI CO LTD. 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 A4:81:7A:00:00:00 to A4:81:7A:FF:FF:FF.

OUI prefix: A4:81:7A
Hyphen form: A4-81-7A
MAC range: A4:81:7A:00:00:00 – A4:81:7A:FF:FF:FF
Addresses in block: 16,777,216
Organization: CIG SHANGHAI CO LTD
Address: 5th Floor, Building 8 No 2388 Chenhang Road SHANGHAI CN 201114
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 CIG SHANGHAI CO LTD

CIG SHANGHAI CO LTD holds 25 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 "CIG SHANGHAI CO LTD"
archived source →
2026-07-17Assigned to "CIG SHANGHAI CO LTD"

Nearby in the registry

The prefixes assigned immediately before and after A4:81:7A:

FAQ

Which company owns MAC address prefix A4:81:7A?: MAC address prefix A4:81:7A is registered to CIG SHANGHAI CO LTD in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:81:7A has a network interface built by CIG SHANGHAI CO LTD.
What is the OUI A4:81:7A?: A4:81:7A is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to CIG SHANGHAI CO LTD. It covers every address from A4:81:7A:00:00:00 to A4:81:7A:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-81-7A.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in A4:81:7A:00:00:00 that is A4:81:7A — 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 CIG SHANGHAI CO LTD located?: CIG SHANGHAI CO LTD is listed at 5th Floor, Building 8 No 2388 Chenhang Road SHANGHAI CN 201114 in the IEEE OUI registry entry for A4:81:7A. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does CIG SHANGHAI CO LTD own?: CIG SHANGHAI CO LTD holds 25 OUI prefixes in the IEEE registry, of which A4:81:7A is one. A device made by CIG SHANGHAI CO LTD could carry a MAC address from any of them.