An 8-port Ethernet switch is configured with VLAN 100 on ports 1-4 and VLAN 200 on ports 5-8. What happens when the switch receives a frame with an unknown destination address on port 1?

When the switch receives a frame with an unknown destination address on port 1, it will flood the frame to all ports that are part of the same VLAN. In this scenario, ports 1-4 are configured for VLAN 100, and ports 5-8 are configured for VLAN 200. Since the received frame is on port 1, which belongs to VLAN 100, the switch will only forward the frame to the other ports that are also part of VLAN 100.

Thus, the correct action taken by the switch is to flood the frame on ports 2, 3, and 4. This behavior is consistent with how Ethernet switches operate, as they do not forward frames to ports that are part of different VLANs (in this case, ports 5-8 which belong to VLAN 200). This VLAN segmentation helps in maintaining traffic isolation and improving overall network security and performance.

Therefore, the flooding of the frame is limited to ports 2 to 4 belonging to the same VLAN, confirming the correctness of this choice.