Cisco Certified Network Associate (CCNA) Practice Exam

In STP, what are the active non-root ports called?

1. Root Ports

2. Designated Ports

3. Alternate Ports

4. Blocking Ports

The correct answer is: Designated Ports

In Spanning Tree Protocol (STP), the active non-root ports are referred to as Designated Ports. These ports are responsible for forwarding traffic toward the root bridge. Essentially, a Designated Port is the port on a network segment that has the lowest path cost to the root bridge, making it the preferred port for data transmission on that segment. The role of Designated Ports is crucial, as they ensure that the data packets can effectively reach their destination while maintaining a loop-free topology. Each segment in an STP topology will have only one Designated Port, which outlines its importance in overall network efficiency. Conversely, Root Ports are designated for non-root bridges, and they represent the port with the best path to the root bridge but do not transmit packets on behalf of the network segment. Alternate Ports serve as backups for a Designated Port and will only take effect if the Designated Port fails. Blocking Ports are used to prevent loops by not forwarding traffic. Hence, while all these terms relate to STP functionality, Designated Ports specifically denote the non-root ports actively forwarding data in a given segment.