What are two actions performed by a Cisco switch? (Choose two.)
A forwarding frames with unknown destination IP addresses to the default gateway
B building a routing table that is based on the first IP address in the frame header
C examining the destination MAC address to add new entries to the MAC address table
D utilizing the MAC address table to forward frames via the destination MAC address
E using the source MAC addresses of frames to build and maintain a MAC address table
The correct answer and explanation is :
The correct answers are:
C. Examining the destination MAC address to add new entries to the MAC address table
D. Utilizing the MAC address table to forward frames via the destination MAC address
Explanation:
A Cisco switch operates at the Data Link Layer (Layer 2) of the OSI model and primarily performs functions related to frame forwarding and address learning. Here’s how the correct answers align with these functions:
C. Examining the destination MAC address to add new entries to the MAC address table
Switches use the MAC address table (also known as the forwarding table) to make decisions about where to send incoming frames. When a frame arrives at the switch, it looks at the destination MAC address. If the destination MAC address is not already in the table, the switch learns the address by associating it with the port on which the frame was received. This allows the switch to forward future frames destined for the same MAC address to the correct port.
Thus, examining the destination MAC address and adding it to the table if it’s unknown is a key function of the switch to ensure efficient and accurate frame forwarding.
D. Utilizing the MAC address table to forward frames via the destination MAC address
Once the switch has built its MAC address table, it uses this table to forward frames to the correct destination. When a frame arrives, the switch checks the destination MAC address in the frame and consults its MAC address table to determine which port to forward the frame to. If the destination MAC address is in the table, the frame is forwarded to the corresponding port. If the destination MAC address is not in the table, the switch will broadcast the frame to all ports, except the one it was received on, to learn the destination’s location.
Switches do not perform IP routing or examine the first IP address in the frame header, which eliminates options A and B. Furthermore, while switches learn MAC addresses from the source MAC address (as mentioned in E), the correct action associated with a switch forwarding frames involves utilizing the destination MAC address, as stated in option D.
Therefore, options C and D correctly describe core actions performed by a Cisco switch.