24-Bit MAC Address Prefix

The First 24 Bits in a MAC Address

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What is the first 24 bits in a MAC address called?



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An Organizationally Unique Identifier (OUI) is a 24-bit number that uniquely identifies a vendor, manufacturer, or other organization globally or worldwide. They are used as the first 24 nits of the MAC address to uniquely identify a particular piece of equipment.

In a MAC (Media Access Control) address, the first 24 bits (3 bytes) are called OUI (Organizationally Unique Identifier).

The OUI is a unique identifier assigned by the IEEE (Institute of Electrical and Electronics Engineers) to manufacturers of network interface controllers (NICs). The OUI serves to identify the vendor or manufacturer of the device that the MAC address belongs to.

The remaining 24 bits in a MAC address are referred to as the NIC (Network Interface Controller) portion, which is unique to each individual device manufactured by that vendor.

The BIA (Burned-In Address) is another term used to describe the MAC address of a network device. It is called a "burned-in" address because it is hard-coded into the device's hardware during the manufacturing process.

The VAI (Vendor Assigned Identifier) is not a standard term used in networking and is not related to MAC addresses or OUIs.