CIRCUITO
CARIOCA TI · DOCUMENTATION
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Network lookup

MAC Vendor Lookup

Identify the organization associated with a MAC address using IEEE-derived registry data.

MACEUI-48OUIIEEEVendor

MAC vendor lookup

Enter a complete EUI-48/MAC address. Common colon, hyphen, dotted and compact representations are accepted.

Example: FC:A1:3E:2A:1C:33 or FCA1.3E2A.1C33
EUI-48

What a MAC vendor lookup can actually identify

A universally administered EUI-48 can be derived from an address block assigned by the IEEE Registration Authority. A registry lookup therefore identifies the organization associated with the relevant assigned block; it does not prove the exact device model, product owner or current manufacturer of the equipment.

IEEE

OUI is important, but it is not the only IEEE MAC allocation size

The traditional MA-L allocation includes a 24-bit OUI, but IEEE also provides MA-M and MA-S address blocks. For that reason, describing every modern MAC vendor lookup as simply matching the first three octets can be an oversimplification.

ADDRESS BITS

Universal/local and individual/group bits change the meaning

In an IEEE 802 MAC address, the least significant bit of the first octet indicates individual versus group addressing, while the next bit indicates universal versus local administration. A locally administered address is not a reliable basis for manufacturer attribution, which is why this tool does not send it to the external vendor API.

PRIVACY

The queried MAC is sent to an external service

For universally administered individual addresses, the normalized MAC is sent by the Circuito Carioca TI server to MACVendors.com to obtain the organization name. Avoid submitting identifiers when organizational policy or privacy requirements prohibit sending them to third-party services.

FAQ

Frequently asked questions

Does every MAC address have a vendor?+

No. Locally administered addresses, randomized addresses, group addresses and addresses not present in the provider database may not produce a meaningful organization match.

What is an OUI?+

An Organizationally Unique Identifier is a 24-bit identifier assigned through the IEEE Registration Authority and is included in an MA-L assignment. It can be used as the organization portion of globally unique extended identifiers.

Why does the tool require all 12 hexadecimal digits?+

A complete MAC lets the provider apply its current allocation database without this page assuming that every assignment is only a traditional 24-bit OUI.

Why is a locally administered MAC not sent to the API?+

Because its U/L bit explicitly indicates local administration. Treating its prefix as a manufacturer assignment could produce a misleading attribution.

Can the result identify the exact device model?+

No. Registry data identifies an organization associated with an address allocation. It does not encode the device model, serial number, owner or current physical location.

Does this tool send the MAC to a third party?+

Yes, for universally administered individual addresses. The server sends the normalized MAC to MACVendors.com to obtain the organization result.

What happens if the API rate limit is reached?+

The provider can return HTTP 429. The tool reports the rate-limit condition separately instead of presenting it as an unknown vendor.

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