STP Troubleshooting STP 3

Question 1

What is Unidirectional Link Detection (UDLD)?

Accepted Answer

A protocol that detects one-way communication failures on fiber links that could cause STP loops

Answer

UDLD monitors bidirectional communication on links, shutting down ports where only one direction is working to prevent STP from making incorrect decisions.

Question 2

What is the impact of incorrect STP timer modifications?

Accepted Answer

Can cause network instability, premature convergence failures, or delayed failover

Answer

Modifying STP timers without understanding the implications can cause ports to transition states too quickly (creating loops) or too slowly (causing unnecessary downtime).

Question 3

How does STP handle a switch receiving superior BPDUs on its root port?

Accepted Answer

The switch updates its root bridge information and recalculates the spanning tree topology

Answer

When a switch receives a superior BPDU (from a bridge with a lower ID), it updates its understanding of the topology and may select a new root bridge and root port.

Question 4

What is the purpose of STP path cost manipulation?

Accepted Answer

To influence which paths STP selects as primary forwarding paths by adjusting port costs

Answer

By adjusting port costs, network administrators can make STP prefer certain paths over others, optimizing traffic flow according to network design goals.

Question 5

What happens when PortFast is incorrectly enabled on a switch-to-switch link?

Accepted Answer

It can cause temporary bridging loops because the port skips listening and learning states

Answer

Enabling PortFast on inter-switch links bypasses STP protection, potentially causing loops during topology changes since the port immediately forwards traffic.

(STP) Spanning Tree Protocol Practice Test

(STP) Spanning Tree Protocol Practice Test

STP Troubleshooting STP 3