What does the Spanning Tree Protocol (STP) primarily prevent in a switched network?

What does the Spanning Tree Protocol (STP) primarily prevent in a switched network?

• A. It routes packets using shortest-path routing.
• B. It encrypts traffic between switches.
• C. It prevents loops in a switched network by disabling redundant paths.
• D. It provides automatic device discovery on the network.

Answer: (C)

Spanning Tree Protocol prevents switching loops by creating a loop-free topology and blocking redundant paths. In a network with multiple switches and redundant links, frames can circulate endlessly if cycles exist, leading to broadcast storms and unstable MAC tables. STP solves this by electing a root bridge, then choosing one best path from the root to every switch and marking all other conflicting ports as blocked. The active paths form a tree, so there’s exactly one active path between any two devices, which stops loops from forming. If a blocked link fails or reconfigures, STP can activate a previously blocked path to maintain connectivity, but it still preserves a loop-free structure overall. This prevents the kind of looping that would otherwise degrade network performance. Other options aren’t what STP does: routing protocols handle path selection across routers (layer 3), encryption is about securing data, and device discovery is done by other protocols. STP’s purpose is specifically to stop loops at the switching layer by disabling redundant paths.

Spanning Tree Protocol prevents switching loops by creating a loop-free topology and blocking redundant paths. In a network with multiple switches and redundant links, frames can circulate endlessly if cycles exist, leading to broadcast storms and unstable MAC tables. STP solves this by electing a root bridge, then choosing one best path from the root to every switch and marking all other conflicting ports as blocked. The active paths form a tree, so there’s exactly one active path between any two devices, which stops loops from forming.

If a blocked link fails or reconfigures, STP can activate a previously blocked path to maintain connectivity, but it still preserves a loop-free structure overall. This prevents the kind of looping that would otherwise degrade network performance.

Other options aren’t what STP does: routing protocols handle path selection across routers (layer 3), encryption is about securing data, and device discovery is done by other protocols. STP’s purpose is specifically to stop loops at the switching layer by disabling redundant paths.