What a MAC address vendor lookup tells you

A MAC address (Media Access Control address) is a unique hardware identifier assigned to every network interface on a device. A laptop’s Wi-Fi adapter, a server’s Ethernet port, a thermostat’s radio — each carries a 48-bit MAC address. It is burned in at the factory. These addresses are written as six pairs of hexadecimal digits separated by colons or dashes. An example is 00:1A:2B:3C:4D:5E. Unlike IP addresses, which change depending on your network, a MAC address is tied to the physical hardware itself. MAC addresses operate at Layer 2 of the OSI model. They are used within a local network segment, not across the internet.

What is an OUI?

The first three octets (six hex characters) of a MAC address form the Organizationally Unique Identifier, or OUI. The IEEE assigns OUI prefixes to manufacturers. So the first half of any MAC address tells you who made the device. When you run a lookup above, it queries the OUI portion against a vendor database. That returns the manufacturer. This is sometimes called an OUI lookup or MAC vendor search. A MAC address starting with 00:1A:2B resolves to a specific networking company. That tells you the hardware brand at a glance. Only the OUI matters for vendor identification. Entering just the first six characters works as well as pasting the full address.

Why look up a MAC address vendor?

• Network troubleshooting: in ARP tables, DHCP leases, or switch port mappings, the vendor helps you tell devices apart. It separates routers, printers, IoT sensors, and workstations on a busy network. See our network troubleshooting guide for more techniques.
• Device identification: if you see an unfamiliar MAC address, the vendor can help you identify the device. It may be an expected smart-home gadget or an unwanted intruder.
• Security auditing: administrators use MAC vendor lookups to inventory hardware. An unexpected manufacturer in DHCP logs can flag a rogue device or policy violation before it grows into a problem.
• Asset management: in environments with thousands of devices, correlating MAC addresses to vendors streamlines hardware inventory. It also helps track device lifecycles.

Randomized and locally administered MAC addresses

If your lookup returns a “locally administered” message instead of a vendor, you have almost certainly entered a randomized address. Modern operating systems randomize Wi-Fi MAC addresses as a privacy feature. Both iOS and Android use a per-network private address by default. Windows offers a random hardware address as a setting. A randomized address is marked by the locally administered bit — bit 1 of the first octet. That bit signals software generated the address, not a manufacturer’s IEEE block. That is why no vendor record exists for it. You can spot one at a glance. The second hex character of a randomized address is always 2, 6, A, or E. Our MAC address guide covers how randomization works and how to find a device’s true hardware address.

This tool resolves the OUI portion of the address you enter against the IEEE vendor database via macaddress.io. NetworkCheckr does not log or store your lookups. Successful results are cached in your own browser, so repeat checks of the same prefix never re-query the service. No installation, no signup — paste an address and go.

MAC address lookup FAQ

Can a MAC address be traced to a person or location?

No. A MAC address lookup reveals only the hardware manufacturer, not an owner or location. MAC addresses operate at Layer 2 and are not routed across the internet. They never travel beyond the local network segment. The IEEE OUI database maps prefixes to companies, not to individual devices or people.

Why does the lookup say my MAC address is locally administered or randomized?

Modern phones and laptops randomize their Wi-Fi MAC addresses for privacy. They set the locally administered bit, which is bit 1 of the first octet. Apple’s iOS, Google’s Android, and Windows all enable this by default. Because the operating system generates randomized addresses rather than the IEEE, no vendor record exists for them.

Can I look up a partial MAC address?

Yes. Only the first six hexadecimal characters — the OUI — are needed to identify the vendor. Entering 00:1A:2B returns the same manufacturer as the full twelve-character address. The last six characters identify the individual device, not the maker.

Are MAC addresses unique?

Each network interface is intended to have a globally unique MAC address, assigned from the manufacturer’s IEEE-registered block. In practice, virtualization software generates its own MAC addresses, and operating systems randomize them for privacy. Rare factory duplicates also exist. So uniqueness is a strong convention rather than an absolute guarantee.

What is the difference between a MAC address and an IP address?

A MAC address is a permanent hardware identifier used for communication within a local network segment at Layer 2. An IP address is a logical, often-changing address used to route traffic between networks at Layer 3. A device keeps the same MAC address everywhere but receives a different IP address on each network it joins. You can check yours with our What Is My IP Address tool.

Why is no vendor found for a valid MAC address?

Several things cause this. The address may be randomized or locally administered, with no IEEE assignment. It may be a virtual machine interface from hypervisor software. The OUI may be very recently registered and not yet in the lookup database. Or there may be a typo in the prefix. Either way, the address can be perfectly valid on the network while still having no vendor record.

Does this tool store the MAC addresses I enter?

NetworkCheckr does not log or store the addresses you look up. The OUI prefix is sent to the macaddress.io vendor database to resolve the manufacturer. Successful results are then cached in your own browser. Repeat lookups do not need to query the service again.

Related tools and resources

Explore more of our free networking tools. Use the What Is My IP Address tool to check your public IP, or run a DNS Lookup to inspect domain records. You can also review common network ports when configuring firewall rules. To go deeper on the concepts behind this tool, start with What Is a MAC Address? and The OSI Model Explained.