CCNA Practice Exam Test Sample – Question 95

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

A. NIC
B. BIA
C. OUI
D. VAI

Correct Answer: C
Section: IP addressing (IPv4 / IPv6)

Explanation:
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.