STP Basics and Concepts 3

Question 1

Which IEEE standard introduced Rapid Spanning Tree Protocol (RSTP)?

Accepted Answer

IEEE 802.1w

Answer

IEEE 802.1w defined RSTP, which provides much faster convergence than the original 802.1D STP.

Question 2

What is the purpose of the Topology Change Notification (TCN) BPDU in STP?

Accepted Answer

To signal that the network topology has changed

Answer

A TCN BPDU is sent upstream toward the root bridge to notify all switches that a topology change has occurred, prompting MAC table flushes.

Question 3

How many seconds does it take for a classic STP port to transition from Blocking to Forwarding by default?

Accepted Answer

50 seconds

Answer

A port spends 15 seconds in Listening and 15 seconds in Learning for a total of 30 seconds before entering Forwarding, but max age (20s) is added when recovering from indirect failures, totaling up to 50 seconds.

Question 4

Which STP port role is used to block traffic and prevent switching loops on non-root, non-designated ports?

Accepted Answer

Alternate port

Answer

In RSTP, the alternate port is the blocking port that provides a standby path to the root bridge.

Question 5

What does STP use path cost to determine?

Accepted Answer

The best path to the root bridge

Answer

STP calculates cumulative path costs to identify the lowest-cost path to the root bridge, which becomes the root port.

(STP) Spanning Tree Protocol Practice Test

(STP) Spanning Tree Protocol Practice Test

STP Basics and Concepts 3