ICND1 Spanning Tree Protocol (STP) 3

Question 1

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

Accepted Answer

IEEE 802.1W

Answer

IEEE 802.1W defines RSTP, which was later incorporated into the revised 802.1D-2004 standard for faster convergence.

Question 2

What is the primary improvement that RSTP provides over traditional STP?

Accepted Answer

Significantly faster convergence time

Answer

RSTP converges in seconds rather than up to 50 seconds for traditional STP by using a peer negotiation mechanism instead of fixed timers.

Question 3

In RSTP, which port role provides a redundant path to the Root Bridge and can quickly replace the Root Port if it fails?

Accepted Answer

Alternate Port

Answer

The Alternate Port in RSTP offers an alternate path to the Root Bridge and transitions rapidly to Root Port if the current Root Port goes down.

Question 4

What does Cisco's Per-VLAN Spanning Tree Plus (PVST+) do differently from standard 802.1D STP?

Accepted Answer

It runs a separate STP instance for each VLAN, allowing per-VLAN Root Bridge placement

Answer

PVST+ runs an independent STP instance per VLAN, enabling per-VLAN Root Bridge elections and traffic load balancing across redundant links.

Question 5

What does the Cisco STP PortFast feature do when configured on a switch access port?

Accepted Answer

It allows the port to bypass Listening and Learning and go directly to Forwarding

Answer

PortFast causes a port to immediately enter the Forwarding state upon link-up, skipping the Listening and Learning transitional states.

(ICND1) Interconnecting Cisco Networking Devices Part 1 Practice Test