What information does a switch record to build its MAC address table?

What information does a switch record to build its MAC address table?

• A. The source Layer 2 address of incoming frames
• B. The destination IP address of outgoing frames
• C. The broadcast address of the network
• D. The VLAN ID associated with the port

Answer: (A)

A switch builds its MAC address table primarily by recording the source Layer 2 addresses of incoming frames. When a switch receives a frame, it examines the source MAC address and the port on which the frame was received. This information is then used to create or update an entry in the MAC address table, associating the source MAC address with the specific port. This process enables the switch to efficiently forward frames by knowing which port to send a frame destined for a particular MAC address. The other options do not contribute to the construction of the MAC address table. The destination IP address of outgoing frames is not relevant to the Layer 2 switching operation, as switches operate at Layer 2 (Data Link Layer) and do not examine Layer 3 (Network Layer) information. The broadcast address, while important in network communications, does not help in building a MAC address table because it is not unique to a specific device. Lastly, while the VLAN ID is important for managing traffic within a VLAN, it does not directly contribute to the MAC address table, which focuses on the MAC addresses of devices connected to various ports.

A switch builds its MAC address table primarily by recording the source Layer 2 addresses of incoming frames. When a switch receives a frame, it examines the source MAC address and the port on which the frame was received. This information is then used to create or update an entry in the MAC address table, associating the source MAC address with the specific port. This process enables the switch to efficiently forward frames by knowing which port to send a frame destined for a particular MAC address.

The other options do not contribute to the construction of the MAC address table. The destination IP address of outgoing frames is not relevant to the Layer 2 switching operation, as switches operate at Layer 2 (Data Link Layer) and do not examine Layer 3 (Network Layer) information. The broadcast address, while important in network communications, does not help in building a MAC address table because it is not unique to a specific device. Lastly, while the VLAN ID is important for managing traffic within a VLAN, it does not directly contribute to the MAC address table, which focuses on the MAC addresses of devices connected to various ports.