CCNA: Cisco Certified Network Associate — Question 1114

How does MAC learning function on a switch?

Answer options

• A. protects against denial of service attacks
• B. sends frames with unknown destinations to a multicast group
• C. adds unknown source MAC addresses to the address table
• D. sends a retransmission request when a new frame is received

Correct answer: C

Explanation

The correct answer is C because a switch learns MAC addresses by adding unknown source MAC addresses to its address table, allowing it to efficiently direct traffic. Option A is incorrect as MAC learning is not specifically designed to protect against denial of service attacks. Option B is also wrong as sending frames with unknown destinations to a multicast group is not part of the MAC learning process. Option D is incorrect since retransmission requests are not related to MAC address learning.