The answer is to configure spanning-tree mode rapid-pvst. This is correct because the exhibit shows VLAN 40 is still running legacy IEEE 802.1D STP, which relies on timers that cause a 30-second convergence delay during uplink flaps, whereas Rapid PVST+ uses the proposal/agreement handshake to achieve sub-second convergence. On the CCNA 200-301 v2 exam, this tests your understanding of spanning tree convergence differences and the practical impact of protocol selection; a common trap is assuming all VLANs automatically inherit rapid behavior when only the global mode is changed without verifying per-VLAN status. Remember that legacy STP waits through listening and learning states (15 seconds each), while Rapid PVST+ bypasses these with synchronized port roles. A useful memory tip: “Rapid says ‘propose and agree’—no waiting, no delay.”
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. A key principle to apply: rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
show spanning-tree summary
Switch is in pvst mode
Root bridge for: VLAN0001 VLAN0010 VLAN0020
Extended system ID is enabled
Portfast Default is disabled
show spanning-tree vlan 40
Spanning tree enabled protocol ieee
Root ID Priority 327...
A switch stack is running PVST+. Users on VLAN 40 lose connectivity for roughly 30 seconds every time the uplink on SW2 flaps. Based on the exhibit, which change would most directly improve convergence for this VLAN?
show spanning-tree summary
Switch is in pvst mode
Root bridge for: VLAN0001 VLAN0010 VLAN0020
Extended system ID is enabled
Portfast Default is disabled
show spanning-tree vlan 40
Spanning tree enabled protocol ieee
Root ID Priority 327...
A
Configure spanning-tree mode rapid-pvst.
Rapid PVST+ is the direct fix for slow STP convergence in this case.
B
Increase the bridge priority on SW2 for VLAN 40.
Why wrong: That changes root election, not the underlying convergence speed shown here.
C
Disable PortFast on all access ports.
Why wrong: PortFast is for edge ports and is not the cause of the 30-second reconvergence.
D
Convert the uplink to a routed port.
Why wrong: That changes the design, but the exhibit specifically points to STP mode.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure spanning-tree mode rapid-pvst.
The output shows VLAN 40 is still using the legacy IEEE STP process, which converges much more slowly than Rapid PVST+. Moving the switch to rapid-pvst mode gives VLAN 40 the faster proposal/agreement behavior that typically cuts convergence time from tens of seconds to a few seconds.
Key principle: Rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Configure spanning-tree mode rapid-pvst.
Why this is correct
Rapid PVST+ is the direct fix for slow STP convergence in this case.
Related concept
Rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state.
✗
Increase the bridge priority on SW2 for VLAN 40.
Why it's wrong here
That changes root election, not the underlying convergence speed shown here.
When this WOULD be correct
In a different scenario where the question asks about optimizing the spanning tree topology for a network with multiple VLANs and where SW2 is not the root bridge, increasing the bridge priority could help in making SW2 the root bridge, potentially improving overall network performance.
✗
Disable PortFast on all access ports.
Why it's wrong here
PortFast is for edge ports and is not the cause of the 30-second reconvergence.
When this WOULD be correct
In a scenario where a question asks about improving convergence time on access ports that are incorrectly configured with PortFast enabled, disabling PortFast could be the correct answer. This would apply if the exam context indicated that the access ports were causing issues due to improper handling of STP states.
✗
Convert the uplink to a routed port.
Why it's wrong here
That changes the design, but the exhibit specifically points to STP mode.
When this WOULD be correct
In a scenario where the question asks how to optimize routing performance for inter-VLAN traffic and reduce latency, converting the uplink to a routed port could be the correct answer. This would be appropriate if the focus was on routing efficiency rather than spanning tree convergence.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
Rapid PVST+ is the direct fix for slow STP convergence in this case.
✗Increase the bridge priority on SW2 for VLAN 40.Wrong answer — click to see why▾
Why this is wrong here
Increasing the bridge priority on SW2 for VLAN 40 would make SW2 more likely to become the root bridge, but it does not change the STP convergence mechanism. The 30-second delay is due to the STP mode (802.1D vs Rapid PVST+), not the root bridge location.
★ When this WOULD be the correct answer
In a different scenario where the question asks about optimizing the spanning tree topology for a network with multiple VLANs and where SW2 is not the root bridge, increasing the bridge priority could help in making SW2 the root bridge, potentially improving overall network performance.
Why candidates choose this
Students may think that making SW2 the root bridge would speed up convergence because the root bridge is central to STP operations. However, root bridge election does not affect the convergence time of individual link flaps; the STP mode is the key factor.
✗Disable PortFast on all access ports.Wrong answer — click to see why▾
Why this is wrong here
Disabling PortFast on access ports would actually increase convergence time for those ports, as PortFast allows edge ports to transition to forwarding immediately. The issue is with the uplink flap, which is not an access port, so disabling PortFast would not help and could worsen convergence for end devices.
★ When this WOULD be the correct answer
In a scenario where a question asks about improving convergence time on access ports that are incorrectly configured with PortFast enabled, disabling PortFast could be the correct answer. This would apply if the exam context indicated that the access ports were causing issues due to improper handling of STP states.
Why candidates choose this
Some might confuse PortFast with features that affect uplink convergence, or think that disabling unnecessary features could improve stability. However, PortFast is designed for access ports and does not impact uplink STP convergence.
✗Convert the uplink to a routed port.Wrong answer — click to see why▾
Why this is wrong here
Converting the uplink to a routed port would remove it from STP entirely, which could cause loops if the uplink is part of a redundant topology. The exhibit shows a switch stack with VLANs, and the uplink is likely a trunk; converting to a routed port would break VLAN trunking and is not a direct fix for the STP convergence issue.
★ When this WOULD be the correct answer
In a scenario where the question asks how to optimize routing performance for inter-VLAN traffic and reduce latency, converting the uplink to a routed port could be the correct answer. This would be appropriate if the focus was on routing efficiency rather than spanning tree convergence.
Why candidates choose this
Routed ports do not participate in STP, so a student might think that eliminating STP on the uplink would avoid convergence delays. However, this ignores the need for loop prevention in a switched network and the fact that the uplink is a trunk carrying multiple VLANs.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting options that change the root bridge election or port roles, such as increasing bridge priority, assuming this will speed up convergence. While root bridge placement affects path selection, it does not reduce the inherent delay caused by legacy STP timers. Another trap is disabling PortFast on access ports, which only affects edge port transitions and does not influence uplink link flap recovery times. Additionally, converting uplinks to routed ports changes the network design and removes STP from those ports, which is not the intended solution for VLAN-specific STP convergence delays. The key mistake is confusing topology optimization with protocol speed improvements.
Trap categories for this question
Command / output trap
That changes root election, not the underlying convergence speed shown here.
Detailed technical explanation
How to think about this question
Spanning Tree Protocol (STP) prevents Layer 2 loops by blocking redundant paths and allowing only one active path between switches. The original IEEE 802.1D STP uses a slow convergence process, requiring ports to pass through listening and learning states before forwarding, which can take 30 to 50 seconds. Rapid PVST+ is Cisco's enhancement that runs a separate instance of STP per VLAN and uses a proposal/agreement handshake to reduce convergence time to a few seconds. This is critical in environments with VLAN segmentation, as each VLAN can recover independently and faster from topology changes.
When a link flap occurs on a switch uplink, legacy STP causes all affected VLANs to undergo slow topology recalculations, resulting in noticeable downtime. Rapid PVST+ improves this by quickly electing port roles and transitioning ports to forwarding state without waiting for timers to expire. Enabling spanning-tree mode rapid-pvst on all switches ensures that VLAN 40 and others benefit from this rapid convergence. This mode is configured globally and affects all VLANs, replacing the default slower STP mode.
A common exam trap is confusing root bridge election changes with convergence speed improvements. Increasing bridge priority only influences which switch becomes root but does not reduce the time STP takes to converge after a topology change. Similarly, disabling PortFast affects edge port behavior and does not impact uplink convergence. Converting uplinks to routed ports removes them from STP but alters network design and is not a direct fix for VLAN-specific STP convergence issues. Understanding these distinctions is essential for correctly troubleshooting and optimizing STP in Cisco networks.
KKey Concepts to Remember
Rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state.
Each VLAN in Rapid PVST+ runs a separate instance of Spanning Tree Protocol, allowing independent topology changes and faster recovery per VLAN.
Legacy STP can cause up to 30-50 seconds of downtime during topology changes due to its slower listening and learning states.
Switches running Rapid PVST+ use Bridge Protocol Data Units (BPDUs) to negotiate port roles and rapidly converge after link failures.
Configuring spanning-tree mode rapid-pvst globally enables all VLANs to benefit from rapid convergence instead of defaulting to slower STP.
PortFast is designed to speed up port transitions on edge ports but does not affect convergence time for VLAN uplink failures.
Changing bridge priority affects root bridge election but does not improve the fundamental convergence speed of the spanning tree protocol.
Converting an uplink port to a routed port removes it from STP but changes network design and does not directly address VLAN-specific STP convergence.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Services and Security — This question tests Network Services and Security — Rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state..
What is the correct answer to this question?
The correct answer is: Configure spanning-tree mode rapid-pvst. — The output shows VLAN 40 is still using the legacy IEEE STP process, which converges much more slowly than Rapid PVST+. Moving the switch to rapid-pvst mode gives VLAN 40 the faster proposal/agreement behavior that typically cuts convergence time from tens of seconds to a few seconds.
What should I do if I get this 200-301 question wrong?
Review rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Rapid PVST+ provides faster convergence than legacy IEEE 802.1D STP by using proposal and agreement handshakes to quickly transition ports to forwarding state.
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