What is an OUI (Organizationally Unique Identifier)?

An OUI is the first 24 bits (3 bytes) of a 48-bit MAC address assigned by the IEEE to hardware manufacturers (e.g., Apple, Cisco, Intel, Samsung) to uniquely identify network interface cards.

What is the difference between Universal and Locally Administered MAC addresses?

Bit 1 of the first byte indicates administration: 0 denotes a globally unique OUI assigned by the manufacturer, while 1 denotes a locally administered address (commonly used in virtual machines, Docker containers, and randomized mobile privacy MACs).

MAC Address OUI Lookup & Generator

Identify network hardware manufacturers from 24-bit OUI prefixes and generate bulk cryptographically random unicast/multicast MAC addresses with customizable separators. 100% private in-browser.

MAC Address Architecture & Frame Standards

IEEE 802.3 MAC Framing

A Media Access Control (MAC) address is a 48-bit physical identifier assigned to Network Interface Controllers (NICs) operating at the OSI Data Link Layer (Layer 2).

Broadcast / Multicast Bit

Bit 0 of the first octet indicates transmission scope: 0 signifies Unicast (directed to a single host), while 1 indicates Multicast or Broadcast (flooded to multiple nodes).

Privacy MAC Randomization

Modern mobile operating systems (iOS and Android) randomize MAC addresses when scanning Wi-Fi networks by setting the Locally Administered bit (Bit 1) to prevent physical tracking.