The figure shows the simplified topology of an enterprise campus network.

An Ethernet switch learns MAC address entries dynamically by examining the source MAC address of incoming frames. When SW1 first receives frames from PC1 on GE1/0/1, it creates a MAC address table entry mapping PC1’s MAC address to that port. If PC1 later sends frames that arrive on GE1/0/2, SW1 updates the learned entry to reflect the new incoming interface. Therefore, option B is correct: SW1 saves the mapping between PC1’s MAC address and GE1/0/2 and removes or overwrites the old mapping associated with GE1/0/1.

Option A is incorrect because a single dynamic MAC address is not normally maintained on two different ports within the same VLAN at the same time; that would cause forwarding ambiguity. Option C is incorrect because a normal move of one MAC address does not require clearing the entire MAC table. Option D is also incorrect because switches update MAC learning dynamically upon receiving new source traffic and do not have to wait for the previous entry to age out. HCIA-Datacom uses this principle to explain MAC address learning, migration, and troubleshooting of loops or host movement in switched Ethernet networks.

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