CCNA Switching and Network Access Practice Question
Exhibit: A switch port connected to an end host is stuck in a blocking state much longer than expected after a reboot. Which configuration change most directly speeds host access while still keeping loop protection elsewhere?
⚠ Common exam trap
Avoid confusing STP parameters like hello time with features like PortFast that directly affect port state transitions.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable PortFast on the access port
PortFast should be enabled on access ports that connect to end devices. It lets the port move to forwarding quickly without waiting through normal STP listening and learning delays. Disabling STP globally removes all loop protection, which contradicts the requirement to keep loop protection elsewhere. Changing the trunk native VLAN is irrelevant to an access port's STP state transition. Adjusting duplex has no effect on STP timers and would not speed up host access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable PortFast on the access port
Why this is correct
Enable PortFast on the access port to bypass the STP listening and learning states, allowing the port to transition directly to forwarding. This is the standard solution for host-facing ports where no switches are connected and loops cannot occur. It ensures the end host obtains an IP address quickly.
- ✗
Disable STP globally
Why it's wrong here
Disabling Spanning Tree Protocol globally eliminates loop protection across the entire switch, risking broadcast storms and MAC address instability if a redundant path exists. It is an unsafe and overly broad action. The intended fix is to apply PortFast only to known host ports, leaving STP active for loop safety.
When this WOULD be correct
In a different scenario where the question asks how to quickly troubleshoot a network experiencing severe broadcast storms due to misconfigured switches, disabling STP globally could be a temporary measure to restore connectivity while resolving the underlying issues.
- ✗
Change the trunk native VLAN
Why it's wrong here
Changing the trunk native VLAN only affects VLAN tagging between switches. It does not alter spanning-tree timers or the port state transition process. An access port stuck in a non-forwarding state due to STP convergence requires PortFast, not a VLAN adjustment.
When this WOULD be correct
In a different scenario where the question asks about resolving VLAN mismatches on a trunk link, changing the trunk native VLAN could be the correct answer. For example, if the native VLAN on both ends of the trunk is misconfigured, it could lead to connectivity issues that this action would resolve.
- ✗
Set the port to half-duplex
Why it's wrong here
Setting the port to half-duplex changes the duplex mode and can introduce collisions on a modern link, but it has no effect on spanning-tree state transitions. The listening and learning delays are governed by STP timers, not physical layer settings. Therefore, this action would degrade performance without resolving the stuck port.
When this WOULD be correct
In a scenario where a question asks how to configure a port for legacy devices that only support half-duplex communication, setting the port to half-duplex would be the correct answer. This would be relevant if the question specifically focused on compatibility with older hardware.
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.
✓Enable PortFast on the access portCorrect answer▾
Why this is correct
Enable PortFast on the access port to bypass the STP listening and learning states, allowing the port to transition directly to forwarding. This is the standard solution for host-facing ports where no switches are connected and loops cannot occur. It ensures the end host obtains an IP address quickly.
✗Disable STP globallyWrong answer — click to see why▾
Why this is wrong here
Disabling STP globally removes all loop protection, which can lead to broadcast storms and network loops if redundant links exist. This is not an acceptable solution because the question explicitly requires keeping loop protection elsewhere.
★ When this WOULD be the correct answer
In a different scenario where the question asks how to quickly troubleshoot a network experiencing severe broadcast storms due to misconfigured switches, disabling STP globally could be a temporary measure to restore connectivity while resolving the underlying issues.
Why candidates choose this
A student might think that disabling STP entirely would eliminate the blocking state delay, but they overlook the critical need for loop prevention in a network with potential redundant paths.
✗Change the trunk native VLANWrong answer — click to see why▾
Why this is wrong here
Changing the trunk native VLAN affects VLAN tagging and potential mismatches but does not influence STP port state transitions. The delay experienced is due to STP convergence, not VLAN configuration.
★ When this WOULD be the correct answer
In a different scenario where the question asks about resolving VLAN mismatches on a trunk link, changing the trunk native VLAN could be the correct answer. For example, if the native VLAN on both ends of the trunk is misconfigured, it could lead to connectivity issues that this action would resolve.
Why candidates choose this
A test-taker might confuse native VLAN issues with STP delays, especially if they have encountered problems where native VLAN mismatch causes connectivity issues, but those are unrelated to the blocking state duration.
✗Set the port to half-duplexWrong answer — click to see why▾
Why this is wrong here
Setting the port to half-duplex does not affect STP state transitions; duplex settings impact collision detection and throughput, not the time a port spends in blocking state. STP timers are independent of duplex configuration.
★ When this WOULD be the correct answer
In a scenario where a question asks how to configure a port for legacy devices that only support half-duplex communication, setting the port to half-duplex would be the correct answer. This would be relevant if the question specifically focused on compatibility with older hardware.
Why candidates choose this
Students might associate half-duplex with slower performance and incorrectly assume it could speed up STP convergence, or they may confuse duplex mismatch issues with STP delays.
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?”
Visual reference
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Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
Access port
An access port is a switch port that connects to a single end device, like a computer or printer, and carries traffic for only one VLAN.
Key term
STP
Shielded Twisted Pair (STP) is a copper cable that wraps each twisted pair in foil or braid to block electromagnetic interference.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.