Which of the following states allows a port to learn MAC addresses?

The state that allows a port to learn MAC addresses is the learning state. In this state, a switch port actively begins to gather information about the devices connected to it. As frames pass through the switch, the port inspects the source MAC addresses of incoming frames and builds a MAC address table, also known as the content addressable memory (CAM) table). This table helps the switch efficiently forward traffic by knowing which MAC addresses are reachable through which ports.

During the learning state, the port does not forward frames to other ports; it solely focuses on learning the MAC addresses present on its own segment. This is essential for improving network efficiency and reducing unnecessary traffic. When a port transitions to the forwarding state after the learning phase, it is fully operational and can both learn MAC addresses and forward frames based on the entries in the MAC address table.

In contrast, other states like blocking and listening do not allow for MAC address learning. Blocking prevents all data frames from being forwarded through the port to prevent network loops, while listening disables frame forwarding but allows for the detection of active loops without learning MAC addresses.