When a frame with a multicast destination MAC address enters a switch, what happens?

When a frame with a multicast destination MAC address enters a switch, what happens?

• A. The switch drops the frame
• B. The switch forwards the frame out all ports except the incoming port
• C. The switch sends the frame only to the designated port
• D. The switch forwards the frame to the default gateway only

Answer: (B)

When a frame with a multicast destination MAC address enters a switch, it is forwarded out all ports except the one on which it was received. This behavior occurs because multicast traffic is intended for multiple devices. In the context of a broadcast domain, multicast frames are designed to reach all interested recipients that have subscribed to that multicast group. By forwarding the frame out of all ports other than the incoming port, the switch ensures that all devices that want to receive the multicast traffic can do so, while preventing the original sender from receiving its own transmission back. This process is fundamental to how multicast communication functions in a network, where a single stream of data needs to reach multiple hosts efficiently without the need to send multiple unicast packets. The switch does not drop the frame since it recognizes the multicast address as valid traffic. It also does not send the frame only to designated ports or forward it directly to a default gateway, as these actions would not achieve the goal of delivering multicast data to all intended recipients within the local network segment.

When a frame with a multicast destination MAC address enters a switch, it is forwarded out all ports except the one on which it was received. This behavior occurs because multicast traffic is intended for multiple devices. In the context of a broadcast domain, multicast frames are designed to reach all interested recipients that have subscribed to that multicast group. By forwarding the frame out of all ports other than the incoming port, the switch ensures that all devices that want to receive the multicast traffic can do so, while preventing the original sender from receiving its own transmission back.

This process is fundamental to how multicast communication functions in a network, where a single stream of data needs to reach multiple hosts efficiently without the need to send multiple unicast packets. The switch does not drop the frame since it recognizes the multicast address as valid traffic. It also does not send the frame only to designated ports or forward it directly to a default gateway, as these actions would not achieve the goal of delivering multicast data to all intended recipients within the local network segment.