CompTIA Network+ Practice Test

Which STP port state is responsible for learning MAC addresses?

1. Listening

2. Learning

3. Forwarding

4. Blocked

The correct answer is: Learning

The port state responsible for learning MAC addresses in Spanning Tree Protocol (STP) is the Learning state. In this state, the switch actively listens to the frames that pass through the port but does not forward them. During this phase, the switch gathers and records the source MAC addresses from the incoming frames into its MAC address table. This allows the switch to know which device is reachable through which port, preparing it for efficient frame forwarding when the port transitions into the Forwarding state. To provide additional context, in the Listening state, the switch identifies and prevents loops but does not learn MAC addresses or forward frames. The Forwarding state does forward frames and maintains the MAC address table, but it is not the state where addresses are first learned. The Blocked state, on the other hand, means that the port is entirely inactive and does not send or receive any frames, thereby having no possibility of learning MAC addresses.