Which of the following statements about MAC addresses is true?

• A. MAC addresses can be changed easily
• B. Every MAC address is unique to each device
• C. MAC addresses are assigned randomly
• D. MAC addresses are the same for all devices

Answer: (B)

The statement that every MAC address is unique to each device is accurate and reflects the fundamental purpose of a MAC address in networking. A Media Access Control (MAC) address is a hardware identifier assigned to network interfaces for communications on the physical network segment. This uniqueness is crucial for the functioning of local networks, as it ensures that each device can be distinctly identified within that network.

MAC addresses are typically assigned by the manufacturer of the network hardware and are stored in the device's network interface card (NIC). They follow a consistent format and are designed to prevent duplication, thus facilitating reliable data transmission between devices without conflict.

While it is possible for some users to change or spoof their MAC address intentionally (as mentioned in the other options), this does not negate the foundational principle that MAC addresses are intended to be unique to each physical device. This uniqueness is vital for the operation of protocols such as Ethernet, which rely on MAC addresses for routing packets of data between specific devices on a network.