MAC Lookup

Look up MAC address vendor information

Accepted formats: XX:XX:XX:XX:XX:XX, XX-XX-XX-XX-XX-XX, XXXXXXXXXXXX.

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Understanding MAC Addresses
TL;DR

A MAC address is a 48-bit hardware identifier assigned to every network interface. The first 24 bits identify the manufacturer (OUI), the last 24 bits are device-specific.

What is a MAC Address?

A MAC address (Media Access Control address) is a unique 48-bit identifier assigned to every network interface controller (NIC) — whether it is an Ethernet port, a Wi-Fi adapter, or a Bluetooth radio. MAC addresses operate at Layer 2 (the Data Link layer) of the OSI model, which means they are used for communication within a local network segment, not for routing across the internet.

Every frame of data transmitted on an Ethernet or Wi-Fi network carries both a source MAC address and a destination MAC address. Switches use these addresses to forward frames to the correct physical port. Unlike IP addresses, which can change as a device moves between networks, a MAC address is typically burned into the hardware at the factory — though modern operating systems now support randomization for privacy.

Think of the MAC address as the device’s “physical name” on the local network, while the IP address is its “logical address” that enables communication across networks.

OUI Explained

The 48-bit MAC address is divided into two equal halves:

  • OUI (Organizationally Unique Identifier): The first 24 bits (3 bytes) identify the hardware manufacturer. The IEEE (Institute of Electrical and Electronics Engineers) assigns OUIs to organizations that request them.
  • NIC-specific (Device Identifier): The last 24 bits (3 bytes) are assigned by the manufacturer to uniquely identify the individual device. Each manufacturer manages this portion independently.
MAC Address Structure — OUI and Device Identifier A diagram breaking down the MAC address AA:BB:CC:DD:EE:FF into its OUI portion (first 3 bytes, manufacturer identifier) and NIC-specific portion (last 3 bytes, device identifier). MAC Address: 00:1B:21:3A:4F:5C 00 1B 21 3A 4F 5C : : : : : OUI — Manufacturer (24 bits) Assigned by IEEE to Intel Corporation NIC — Device Specific (24 bits) Assigned by manufacturer to this device Special bits in byte 1: Bit 0 (LSB): 0 = Unicast, 1 = Multicast Bit 1: 0 = Globally unique (OUI enforced), 1 = Locally administered 00:1B:21:... has bit 0 = 0 and bit 1 = 0 This is a globally unique unicast address (factory-assigned)

This structure means that given any MAC address, you can look up the first three bytes against the IEEE OUI database to identify the manufacturer. Our MAC Lookup tool does exactly this — paste a MAC address and instantly see which company made the network interface.

Top OUI Assignments

OUI PrefixManufacturerNotes
00:1B:21Intel CorporationCommon in laptops and servers
3C:22:FBApple, Inc.iPhones, MacBooks, iPads
8C:45:00Samsung ElectronicsPhones, TVs, appliances
00:00:0CCisco SystemsSwitches, routers, APs
F8:BC:12Dell TechnologiesServers, workstations

Apple and Samsung each hold hundreds of OUI assignments due to their massive device production volumes. A single OUI provides 2^24 = 16,777,216 unique device addresses, and a company producing more than that number of interfaces per OUI will need additional assignments.

MAC Address Formats

MAC addresses are represented in several notations depending on the operating system and context:

FormatExampleUsed By
Colon-separated00:1B:21:3A:4F:5CLinux, macOS, Wireshark
Hyphen-separated00-1B-21-3A-4F-5CWindows, IEEE standard
Dot-separated (Cisco)001B.213A.4F5CCisco IOS, network equipment
Bare (no separator)001B213A4F5CCompact storage, databases

All four formats represent the same 48-bit address. When validating or looking up a MAC address, a good tool normalizes the input to a canonical format regardless of how the user enters it.

Randomized MAC Addresses

Modern operating systems have introduced MAC address randomization as a privacy measure. Before this feature, a device always broadcast the same MAC address when scanning for Wi-Fi networks, allowing retailers, advertisers, and trackers to monitor a person’s movements across physical locations.

With randomization enabled:

  • Probe requests (Wi-Fi scans) use a random, locally-administered MAC address
  • Per-network MACs assign a different persistent random MAC to each saved Wi-Fi network
  • The real hardware MAC is only used when actually associated with a network (and even this varies by OS)

You can identify a randomized MAC by checking the second character of the first byte: if it is 2, 6, A, or E, the locally administered bit is set, indicating the address was software-generated rather than factory-assigned.

Common Use Cases

  • Device identification: Network administrators use MAC addresses and OUI lookups to identify which manufacturer’s hardware is connected to their network
  • Network access control (NAC): Enterprises use MAC-based authentication (802.1X) to restrict which devices can connect to corporate LANs
  • DHCP reservations: Assign a consistent IP address to a device by mapping its MAC address in the DHCP server configuration
  • Troubleshooting: When diagnosing network issues, MAC addresses help trace traffic at the switch level and identify rogue devices
  • Asset inventory: MAC OUI lookups help classify network-connected devices by manufacturer for inventory and compliance audits
  • Forensics: In security investigations, MAC addresses in ARP tables and switch logs help reconstruct which devices were present on the network at a given time

Try These Examples

Valid MAC Address (Intel) Valid

A valid MAC address with the OUI 00:1B:21 registered to Intel Corporation. The format uses colon-separated hexadecimal pairs, one of the standard MAC notations.

00:1B:21:3A:4F:5C
Invalid MAC Address Invalid

Invalid because hexadecimal digits only range from 0-9 and A-F. The character Z is not a valid hex digit, making this address unparseable.

ZZ:ZZ:ZZ:ZZ:ZZ:ZZ