STP Advanced Features and Variants 2

Question 1

What does MSTP (802.1s) allow that RSTP alone does not?

Accepted Answer

Multiple VLANs mapped to different spanning tree instances

Answer

Faster convergence than RSTP

Answer

Port authentication before STP participation

Answer

Dynamic VLAN assignment based on MAC addresses

Question 2

In MSTP, what is the Common and Internal Spanning Tree (CIST)?

Accepted Answer

A spanning tree that interconnects all MST regions and the CST

Answer

The spanning tree used only inside a single MST region

Answer

A redundant backup spanning tree for failover

Answer

The spanning tree used exclusively for native VLAN traffic

Question 3

Which STP variant was specifically designed to reduce convergence time to under one second by using a proposal/agreement handshake?

Accepted Answer

RSTP (802.1w)

Answer

Classic STP (802.1D)

Answer

PVST+

Answer

MSTP (802.1s)

Question 4

What is the function of the MST region in MSTP?

Accepted Answer

A group of switches sharing the same MST configuration name, revision, and VLAN-to-instance mapping

Answer

A group of switches running the same IOS version

Answer

A logical grouping of ports in PortFast mode

Answer

A set of VLANs assigned to the native VLAN trunk

Question 5

Which STP feature prevents a port from becoming a root port by ignoring received superior BPDUs?

Accepted Answer

Root Guard

Answer

PortFast

Answer

BPDU Guard

Answer

Loop Guard

Question 6

In Rapid PVST+, what happens when a non-edge port receives a BPDU on a port that was previously in Forwarding state due to Dispute mechanism?

Accepted Answer

The port is placed in Discarding state to prevent unidirectional link loops

Answer

The port transitions immediately to Blocking

Answer

The port sends a TCN to the root bridge

Answer

The port starts a new timer equal to MaxAge

Question 7

What is the primary advantage of PVST+ over classic 802.1D STP?

Accepted Answer

It runs a separate spanning tree instance per VLAN, enabling per-VLAN load balancing

Answer

It eliminates the need for a root bridge entirely

Answer

It uses only one BPDU for all VLANs to reduce overhead

Answer

It replaces BPDUs with LLDP for topology discovery