Cisco Certified Network Associate (CCNA) Practice Exam

What role does the Backup Port hold in RSTP?

1. It is the primary forwarding port.

2. It acts as a backup for the Root Port.

3. It serves as backup for the Designated Port.

4. It is used when there is no other backup.

The correct answer is: It serves as backup for the Designated Port.

The Backup Port in Rapid Spanning Tree Protocol (RSTP) serves as a secondary port that provides redundancy for the Designated Port on a shared segment. If the Designated Port goes down or fails, the Backup Port can immediately take over to maintain network connectivity without causing a topology change. This ensures the network remains stable and minimizes any potential disruption to data flow. In scenarios where multiple switches are connected to the same network segment, one switch is designated as the Designated Port, responsible for forwarding traffic on that segment. The Backup Port stands ready to take over in case of issues with the Designated Port, which enhances reliability and efficiency in network operations. Choosing this option highlights an important concept within RSTP, where maintaining an efficient path and ensuring redundancy is crucial to reducing potential downtime. The focus for Backup Ports is specifically tied to their role associated with Designated Ports, not the Root Port or general functionality without a counterpart.