24-Bit MAC Address: Understanding Its Significance | Cisco Exam 200-125

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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A. B. C. D.


The first 24 bits in a MAC address represent the Organizationally Unique Identifier (OUI).

An OUI is a unique number that is assigned by the Institute of Electrical and Electronics Engineers (IEEE) to identify the manufacturer of a network interface controller (NIC). The OUI is used to identify the vendor or manufacturer of the device and is unique to that vendor or manufacturer.

For example, a MAC address with an OUI of 00-50-C2 belongs to the vendor "3Com Corporation." The remaining 24 bits in a MAC address represent the device's unique identifier, which is assigned by the manufacturer.

Option C is the correct answer as it stands for Organizationally Unique Identifier. Option A (NIC) stands for Network Interface Card, which is a hardware component that allows a computer to connect to a network. Option B (BIA) stands for Burned-In Address, which is a MAC address that is physically burned into the NIC by the manufacturer. Option D (VAI) is not a commonly used term in networking and does not have any relevance to MAC addresses.