When a host receives a frame addressed to a MAC that is not in the host's own table, what action does the host take?

• A. The host forwards the frame to all other hosts.
• B. The host will discard the frame.
• C. The host processes the frame.
• D. The host replies to the switch with its own IP address.

Answer: (B)

A host only processes frames that are addressed to its own MAC address. When a frame arrives with a destination MAC that does not match the host’s NIC, the hardware immediately discards it, because it isn’t intended for this device. This keeps processing limited to frames meant for the host and avoids wasting CPU cycles on irrelevant traffic. Only in special cases, like being in promiscuous mode (for packet capture) or when the frame is a broadcast or multicast addressed to multiple hosts, would the host handle frames differently. For a unicast frame addressed to a MAC not in this host’s table, the correct action is to discard it.