CCNA Switching and Network Access Practice Question
Exhibit
SW1# show spanning-tree vlan 10 detail
VLAN0010 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address aabb.cc00.0200
Configured hello time 2, max age 20, forward delay 15
Current root has priority 32768, address aabb.cc00.0100
Root port is GigabitEthernet0/2, cost of root path is 4
Topology change flag not set, detected flag not set
Number of topology changes 2 last change occurred 00:05:30 ago
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0
Port 13 (GigabitEthernet0/1) of VLAN0010 is listening
Port path cost 4, Port priority 128, Port Identifier 128.13
Designated root has priority 32768, address aabb.cc00.0100
Designated bridge has priority 32768, address aabb.cc00.0200
Designated port id is 128.13, designated path cost 0
Timers: message age 0, forward delay 12, hold 0
Number of transitions to forwarding state: 0
Link type is point-to-point by default
BPDU: sent 2, received 0
Edge port: no (default) portfast: no (default)Refer to the exhibit. An engineer configured PortFast on interface GigabitEthernet0/1, which connects to a server that does not participate in spanning tree. However, the port remains in the listening state for the full forward delay period before transitioning to forwarding. The engineer issues the show spanning-tree vlan 10 detail command. Based on the output, what is the most likely cause?
⚠ Common exam trap
Cisco often tests the misconception that PortFast works on any port type, but the trap here is that PortFast is only effective on access ports, and trunk ports automatically disable PortFast regardless of configuration.
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
✓
The port is configured as a trunk, so PortFast is not active.
PortFast is designed to immediately transition a port to the forwarding state, bypassing the listening and learning states. However, PortFast is only effective on access ports; if the interface is configured as a trunk port, PortFast is automatically disabled by the switch. The output of 'show spanning-tree vlan 10 detail' would confirm the port is a trunk, explaining why it still goes through the full forward delay.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The port is configured as a trunk, so PortFast is not active.
Why this is correct
PortFast is only effective on access ports. The exhibit shows ‘Edge port: no (default) portfast: no (default)’ despite the engineer enabling PortFast, indicating the port is operating as a trunk (or not an access port). Therefore, PortFast has no effect and the normal STP listening/learning states apply.
- ✗
BPDU Guard is enabled on the port, causing it to block.
Why it's wrong here
BPDU Guard is a defensive STP feature that, when enabled on a PortFast access port, immediately transitions the port to an err-disabled state upon receiving any BPDU. The exhibit, however, shows the port in the normal listening state with zero BPDUs received, and no bpduguard flag is present in the interface output. A port blocking due to BPDU Guard would appear as err-disabled, not in the listening state, so this cannot explain the observed behavior.
- ✗
The forward delay timer is set too high, and PortFast cannot override it.
Why it's wrong here
PortFast is specifically designed to bypass the spanning-tree listening and learning states and transition directly to forwarding, regardless of the configured forward-delay timer value. Even if the forward-delay were set to an unusually high value, PortFast would still skip those interim states because it overrides the aging timers for edge ports. Since the exhibit confirms PortFast is not active (edge port is no), the port remains subject to normal STP state transitions, but the culprit is the port's trunk mode, not the timer.
- ✗
The server is sending BPDUs, causing the port to lose its PortFast state.
Why it's wrong here
If the port received a BPDU after PortFast enabled, it would lose PortFast and revert to normal STP states. However, the exhibit shows ‘BPDU: received 0’ (no BPDUs received), so this is not the cause.
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.
✓The port is configured as a trunk, so PortFast is not active.Correct answer▾
Why this is correct
PortFast is only effective on access ports. The exhibit shows ‘Edge port: no (default) portfast: no (default)’ despite the engineer enabling PortFast, indicating the port is operating as a trunk (or not an access port). Therefore, PortFast has no effect and the normal STP listening/learning states apply.
✗BPDU Guard is enabled on the port, causing it to block.Wrong answer — click to see why▾
Why this is wrong here
The port is not in an err-disabled state; BPDU Guard causes the port to be shut down, not to stay in listening.
✗The forward delay timer is set too high, and PortFast cannot override it.Wrong answer — click to see why▾
Why this is wrong here
Misunderstanding that PortFast bypasses timers completely on access ports; the high forward delay is irrelevant if PortFast were active.
✗The server is sending BPDUs, causing the port to lose its PortFast state.Wrong answer — click to see why▾
Why this is wrong here
The assumption that the server is sending BPDUs is contradicted by the output showing zero BPDUs received.
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
Go deeper
Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
Forwarding state
A Spanning Tree Protocol port state where the port is fully operational, forwarding both data frames and BPDUs, and is part of the active loop-free topology.
Key term
VLAN
A VLAN logically segments a physical network into isolated broadcast domains without requiring separate physical switches.
About these practice questions
This 200-301 question is part of Courseiva's 1,389-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
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.