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MAC Address Lookup
Look up, analyze, validate, and batch-process MAC addresses with vendor information, IEEE assignment details, address type, administration mode, I/G and U/L bits, privacy/randomization indicators, EUI-64 conversion, and IPv6 link-local information.
Supported formats: AA:BB:CC:DD:EE:FF, AA-BB-CC-DD-EE-FF, AABBCCDDEEFF, AABB.CCDD.EEFF
What Is a MAC Address Lookup?
A MAC Address Lookup is a networking tool that analyzes a Media Access Control (MAC) address and provides useful information about the address. A MAC address is a unique 48-bit identifier normally associated with a network interface such as Ethernet, Wi-Fi, or another network adapter.
Our free MAC Address Lookup tool can identify the MAC address format, address type, administration mode, I/G bit, U/L bit, possible randomization indicators, EUI-64 value, and an example IPv6 link-local address. When vendor assignment data is available, the tool can also display the organization, registry, assignment, country, and related information.
How Does MAC Address Lookup Work?
Enter a MAC address into the lookup field and click Lookup. The tool first validates and normalizes the address so that different MAC formats can be processed consistently.
The tool then analyzes the first byte of the MAC address to determine whether the address is unicast or multicast and whether it is universally administered or locally administered. If vendor assignment information is available in the database, the corresponding organization and assignment details are also returned.
MAC Address Lookup Features
- MAC Vendor Lookup: The tool can identify the organization associated with a MAC address when a matching IEEE assignment is available in the vendor database. The result may include the organization, assignment, registry type, country, and address information.
- MAC Address Validation: The validator checks whether a MAC address contains exactly 12 hexadecimal characters and supports common formats such as colon, hyphen, Cisco-style dotted, and plain hexadecimal notation.
- MAC Address Type Detection: The tool determines whether the address is unicast, multicast, or broadcast based on the MAC address bits.
- Locally Administered Detection: The U/L bit is analyzed to determine whether the MAC address is universally administered or locally administered. Locally administered addresses are commonly used for manually assigned or privacy-oriented MAC addresses.
- Randomization Indicator: A locally administered MAC address can indicate that the address may have been manually assigned or randomized. The tool identifies this as a potential randomization indicator, but it does not claim that every locally administered address is randomized.
- I/G Bit Analysis: The Individual/Group (I/G) bit is the least significant bit of the first MAC address byte. A value of 0 indicates an individual or unicast address, while a value of 1 indicates a group or multicast address.
- U/L Bit Analysis: The Universal/Local (U/L) bit indicates whether the MAC address is universally administered or locally administered. A value of 0 normally represents universal administration and a value of 1 represents local administration.
- EUI-64 Conversion: The tool can convert a 48-bit MAC address into an EUI-64 identifier. During the conversion, the U/L bit is inverted and FFFE is inserted between the original OUI and device-specific portions.
- IPv6 Link-Local Example: After generating the EUI-64 value, the tool can construct an example IPv6 link-local address using the FE80:: prefix.
- Batch MAC Lookup: Batch Lookup allows you to submit multiple MAC addresses at once. Enter one MAC address per line and analyze up to 1000 addresses in a single request. Results can also be downloaded as a CSV file.
- Multiple Output Formats: MAC addresses can be displayed in several common formats, including colon-separated, hyphen-separated, Cisco-style dotted, and plain hexadecimal notation.
Supported MAC Address Formats
The tool accepts several commonly used MAC address formats. You can enter the same 48-bit MAC address using different separators or without separators.
- Colon:
AA:BB:CC:DD:EE:FF - Hyphen:
AA-BB-CC-DD-EE-FF - Plain:
AABBCCDDEEFF - Cisco:
AABB.CCDD.EEFF
Understanding MAC Address Analysis
After a successful lookup, the tool presents several technical properties of the MAC address. These values are calculated from the address itself and, where applicable, matched against the vendor assignment database.
- Vendor: The organization associated with the matching MAC assignment, when available.
- Assignment: The assignment information associated with the MAC address prefix.
- Registry: The assignment registry category, such as an applicable IEEE MAC assignment type.
- Country: The country associated with the vendor assignment data, when available.
- Address Type: Indicates whether the MAC address is unicast, multicast, or broadcast.
- Administration: Indicates whether the MAC address is universally or locally administered.
- I/G Bit: Identifies whether the address represents an individual or group address.
- U/L Bit: Indicates universal or local administration of the MAC address.
How Batch MAC Lookup Works
If you need to analyze multiple network devices, entering addresses individually can be time-consuming. The Batch Lookup feature lets you enter one MAC address per line and process multiple addresses together.
The results display the MAC address, vendor, registry, country, address type, administration mode, and potential randomization indicator. You can export the results as a CSV file for further analysis.
How the MAC Address Validator Works
The MAC Address Validator checks whether the value you entered follows the expected structure of a 48-bit MAC address. It accepts hexadecimal characters and common separators such as colons, hyphens, and dots.
A valid MAC address contains 12 hexadecimal characters after separators are removed. For example, 00:1A:2B:3C:4D:5E contains six bytes and is a valid 48-bit MAC address format.
MAC Address to EUI-64 Conversion
EUI-64 is a 64-bit identifier that can be derived from a 48-bit MAC address. The conversion separates the MAC address into its first and second portions, inserts FFFE in the middle, and inverts the Universal/Local bit.
For example, a MAC address such as DE:0C:4A:BD:7B:AF can be converted into an EUI-64 value that can then be represented in IPv6 interface identifier form.
What Does "Potentially Randomized" Mean?
Modern operating systems and mobile devices may use locally administered MAC addresses to improve privacy when connecting to Wi-Fi networks. Because the U/L bit is set, a locally administered address can indicate that the address was not assigned as a traditional universally administered hardware identifier.
However, the U/L bit alone cannot prove that a MAC address was generated randomly. The tool therefore reports this as a potential randomization indicator rather than claiming that the address is definitely randomized.
Frequently Asked Questions
What is a MAC address?
A MAC address is a 48-bit hardware or network interface identifier commonly used at the data-link layer of computer networks. It is normally represented as six hexadecimal bytes.
What information can a MAC lookup provide?
Depending on the available vendor assignment data, a MAC lookup can provide organization, assignment, registry, and country information. The tool also analyzes technical properties such as address type, administration mode, I/G bit, U/L bit, EUI-64, and IPv6 information.
Why does my MAC lookup show Vendor Unknown?
Vendor information is displayed only when the MAC address matches available assignment data. A MAC address can show "Unknown" when there is no matching assignment in the database, particularly for locally administered, randomized, private, or otherwise unassigned addresses.
What does a locally administered MAC address mean?
A locally administered MAC address has its U/L bit set to 1. It can be manually assigned, generated by software, or used as a privacy address. It does not necessarily identify the original hardware manufacturer.
What is the I/G bit?
The I/G bit is the Individual/Group bit in the first byte of a MAC address. A value of 0 represents an individual or unicast address, while a value of 1 represents a group or multicast address.
What is the U/L bit?
The U/L bit is the Universal/Local bit in the first byte of a MAC address. A value of 0 normally indicates universal administration, while a value of 1 indicates local administration.
What is the difference between unicast and multicast MAC addresses?
A unicast MAC address identifies an individual network interface, while a multicast MAC address is used to identify a group of network interfaces. The distinction is determined by the I/G bit.
What is EUI-64?
EUI-64 is a 64-bit identifier that can be derived from a 48-bit MAC address. It is commonly associated with IPv6 interface identifier construction.
Can I look up multiple MAC addresses?
Yes. The Batch Lookup feature allows you to enter multiple MAC addresses, one per line, and process up to 1000 addresses in a request. The results can be downloaded as a CSV file.
What MAC address formats are supported?
The tool supports colon-separated, hyphen-separated, plain hexadecimal, and Cisco-style dotted formats, such as AA:BB:CC:DD:EE:FF, AA-BB-CC-DD-EE-FF, AABBCCDDEEFF, and AABB.CCDD.EEFF.