STP Clinical & Scientific Knowledge 2

Question 1

Which STP port state actively forwards frames AND learns MAC addresses?

Accepted Answer

Forwarding

Answer

Only the Forwarding state both learns MAC addresses and actively forwards data frames.

Question 2

What is the default Hello Time interval in 802.1D STP?

Accepted Answer

2 seconds

Answer

The default Hello Time is 2 seconds, meaning the root bridge sends BPDUs every 2 seconds.

Question 3

A non-root bridge receives a superior BPDU on its root port. What action does STP take?

Accepted Answer

It updates its root port and recalculates the topology

Answer

When a non-root bridge receives a superior BPDU, it updates its root port selection and recalculates path costs.

Question 4

Which STP mechanism prevents a port from immediately transitioning to Forwarding after a link comes up?

Accepted Answer

Forward Delay timer

Answer

The Forward Delay timer (default 15 seconds) holds ports in Listening and Learning states before transitioning to Forwarding.

Question 5

In STP, what does a Topology Change Notification (TCN) BPDU cause receiving switches to do?

Accepted Answer

Age out MAC table entries faster

Answer

TCN BPDUs cause switches to shorten their MAC address aging timer from 300 seconds to the Forward Delay (15 seconds).

(STP) Spanning Tree Protocol Practice Test