refer to the exhibit. how is a frame sent from pca forwarded to pcc if the mac address table on switch sw1 is empty?

The frame from PCA is flooded out all ports on SW1 except the one it came in on.

What the switch actually does

When SW1 receives the frame from PCA and its MAC address table is empty, it does not yet know on which port PCC is located. Because the destination MAC address is unknown, the switch uses flooding: it sends that same frame out every other active port except the ingress port where PCA is connected. One of those flooded copies reaches the port toward PCC, and when PCC replies, SW1 learns PCC’s MAC address and port and adds it to its MAC table for future unicast forwarding.

So, in the wording used in exam-style questions, the correct choice is:

SW1 floods the frame on all ports on SW1, excluding the port through which the frame entered the switch.

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