Final answer:
A switch floods a frame out of all ports except the port it came in on if the destination MAC address is not in its CAM table. Flooding ensures the frame reaches its destination and allows the switch to learn the correct port for future traffic to that MAC address. This process is unrelated to ARP requests or the default gateway.
Step-by-step explanation:
When a switch receives a frame and the destination MAC address is not present in its Content Addressable Memory (CAM) table, the switch performs an action known as flooding. This means that it forwards the frame out of all its ports except the port that it received the frame on. This process ensures that the frame reaches its intended destination even if the switch doesn't know exactly which port to use. Once the recipient device responds, the switch can capture the MAC address and update its CAM table accordingly. Flooding is essentially a discovery process used to determine the right port for future frames addressed to that MAC address.
It's important to note that flooding occurs only for unicast frames with unknown destinations. In contrast, broadcast and multicast frames are always flooded. Flooding does not apply to frames destined for a MAC address that the switch has marked as inactive or 'aged out' of the CAM table; in such cases, the frame would be discarded. Additionally, flooding is not related to Address Resolution Protocol (ARP) requests (which are sent by hosts to discover the MAC address associated with an IP address) or interactions with a default gateway (which is used for routing traffic to different networks).