Network & IP Reference

MAC Address Reference Chart

Quick reference for MAC address structure, OUI prefix lookups, address type bits, common vendor prefixes, and address format normalisation. Use for fast planning, then use the lookup tool to query any specific MAC.

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Terms

MACMedia Access Control address: A unique serial number built into every network device (like a network card or Wi-Fi chip) at the factory — no two devices in the world should share one. It identifies a device on a local network.
OUIOrganizationally Unique Identifier: The first part of a MAC address, which identifies the manufacturer that made the device — so you can look up a MAC address and find out which company built it.

MAC address structure

A MAC address is 48 bits (6 bytes) long. The first 3 bytes are the OUI (Organisationally Unique Identifier) assigned by IEEE to the manufacturer. The last 3 bytes are assigned by the manufacturer to the specific device.

[ OUI — 3 bytes / 24 bits ] : [ NIC-specific — 3 bytes / 24 bits ]

Two control bits in the first byte carry important meaning:

Bit 0 (LSB of byte 1)

0 = Unicast1 = Multicast

Bit 1 of byte 1

0 = Globally administered1 = Locally administered

Address types quick reference

Understanding address type before performing OUI lookup avoids false vendor matches.

Type	Bit pattern	Meaning	Example
Unicast	`Bit 0 of byte 1 = 0`	Sent to a single device	`00:1A:2B:3C:4D:5E`
Multicast	`Bit 0 of byte 1 = 1`	Sent to a group of devices	`01:00:5E:00:00:01`
Broadcast	`All bits = 1`	Sent to all devices on segment	`FF:FF:FF:FF:FF:FF`
Globally administered	`Bit 1 of byte 1 = 0`	Assigned by IEEE to a manufacturer	`00:1A:2B:xx:xx:xx`
Locally administered	`Bit 1 of byte 1 = 1`	Assigned locally — not by manufacturer	`02:00:00:xx:xx:xx`

Common vendor OUI prefixes

These OUI prefixes are reliable only when the MAC is globally administered (bit 1 = 0). Locally administered MACs (randomised by OS) will not match real vendor OUI assignments.

OUI prefix	Vendor	Notes
`00:00:0C`	Cisco Systems	Network equipment, routers, switches
`00:1A:2B`	Cisco Systems	Common in managed switch hardware
`00:50:56`	VMware	VMware virtualised NICs
`00:0C:29`	VMware	VMware Workstation / Fusion VMs
`B8:27:EB`	Raspberry Pi Foundation	Raspberry Pi boards (older)
`DC:A6:32`	Raspberry Pi Foundation	Raspberry Pi 4 and newer
`00:1B:63`	Apple	MacBooks, iMacs, AirPorts
`A4:C3:F0`	Apple	iPhones, iPads — recent models
`8C:85:90`	Intel	Intel NICs, Wi-Fi adapters
`00:90:F5`	Samsung Electronics	Samsung consumer and enterprise
`24:A4:3C`	Ubiquiti	UniFi APs, EdgeRouters, USGs
`74:83:C2`	Ubiquiti	UniFi switches and access points
`2C:54:2D`	Hewlett-Packard	HP ProCurve / Aruba switches
`00:30:48`	Supermicro	Server motherboard NICs
`00:1D:AA`	Dell	Dell PowerEdge servers

Note:IEEE registers over 30 000 OUI blocks. This table covers only commonly encountered prefixes in data centre and network environments. Use the full OUI lookup tool for any specific MAC address.

Address format guide

MAC addresses appear in different formats depending on the operating system or tool. Always normalise before comparing addresses from different sources.

Format	Name / Source	Common
`00:1A:2B:3C:4D:5E`	Colon-separated hex (IEEE standard)	✓
`00-1A-2B-3C-4D-5E`	Hyphen-separated hex (Windows)	✓
`001A.2B3C.4D5E`	Cisco dot-separated	✓
`001A2B3C4D5E`	Unseparated 12-hex string	—
`001a2b3c4d5e`	Lowercase unseparated	—

Normalise: strip separators → uppercase → compare first 6 chars for OUI

How to use this chart

Strip all formatting (colons, hyphens, dots) to get the raw 12 hex characters.
Uppercase the result.
Check bit 0 of the first byte: 0 = unicast, 1 = multicast.
Check bit 1 of the first byte: 0 = globally administered, 1 = locally administered.
If locally administered, stop — OUI lookup will return meaningless results.
Extract the first 3 bytes (OUI prefix) and compare against the vendor database.
Use the full MAC for ARP tables, network inventory, and port security.

Common mistakes

Looking up vendor on a locally administered (randomised) MAC — the OUI is not the real manufacturer.
Confusing multicast MACs with real device addresses in ARP tables.
Not normalising case or separators before comparing MACs from different sources.
Using OUI alone to identify devices in a BYOD or IoT environment (OS randomises MACs by default).
Treating broadcast FF:FF:FF:FF:FF:FF as a device address.

MAC randomisation:iOS 14+, Android 10+, Windows 11, and most modern Linux distributions randomise MAC addresses per Wi-Fi network by default. Expect locally administered MACs from most modern mobile and laptop devices.

FAQ

Why does the OUI lookup return "Unknown vendor"?

Either the OUI is not in the bundled database, the MAC is locally administered (randomised), or the address is a multicast or broadcast address. Check bit 1 of the first byte before assuming the vendor is simply not in the database.

How do I tell if a MAC is randomised?

Check bit 1 (second-least-significant bit) of the first byte. If it is 1, the address is locally administered. In hex: first byte values with second bit set include 02, 06, 0A, 0E, 12, 16, 1A, 1E, 22, 26, 2A, 2E, 32, 36, 3A, 3E, and so on.

What is the difference between OUI and MAC address?

A MAC address is the full 48-bit (6-byte) hardware identifier. The OUI is the first 3 bytes of the MAC, assigned by IEEE to a specific manufacturer. The remaining 3 bytes are the NIC-specific portion, assigned by the manufacturer.

Can I use MAC addresses for network inventory?

Yes, for wired infrastructure and devices with MAC randomisation disabled. For wireless inventory, rely on persistent identifiers (hostnames, device certificates, LLDP/CDP) rather than MACs alone, since randomisation makes MAC-based tracking unreliable.

Disclaimer

This reference chart provides planning guidance only. OUI vendor information may be incomplete or outdated. MAC address randomisation makes vendor identification unreliable for locally administered addresses. Always verify device identity through additional means in security-sensitive contexts.