How does STP prevent loops in a network?

• A. Shutting down redundant links
• B. Flood frames indefinitely
• C. Increasing port speeds
• D. Blocking all traffic on the network

Answer: (A)

Spanning Tree Protocol creates a loop-free network by building a single active path between devices and turning off the redundant ones. It chooses a root switch and then designates one best path to the root for every segment, placing all other potential paths into a blocking state. Those blocked ports don’t forward frames, so even with multiple physical links, there’s only one active path at a time, which prevents loops. When the network changes, STP can reactivate a previously blocked link if that maintains a safer, shorter path, keeping the topology loop-free. This is why the approach is to shut down redundant links rather than flood frames, automatically speed up ports, or block all traffic.