CCNA DC FAQ: Spanning Tree Protocol Concepts Figure: What STP Does: Blocks a Port to Break the Loop Q1. Which of the following IEEE 802.1D port states are stable states used when STP has completed convergence? (Choose three answers.) a. Blocking b. Forwarding c. Listening d. Learning e. Discarding Answer: A and B. Listening and learning are transitory port states, … [Read more...]