- A
The RSPAN VLAN is not allowed on the trunk links between the switches.
Correct because the RSPAN VLAN must be permitted on all intermediate trunks for the monitored traffic to traverse the network.
- B
The destination port is configured as an access port in VLAN 100.
Why wrong: Incorrect because the destination port should be in the RSPAN VLAN, but that alone does not cause the issue; the traffic must first reach the remote switch.
- C
The source switch does not have the RSPAN VLAN configured as a remote-span VLAN.
Why wrong: Incorrect because the RSPAN VLAN is created with the 'remote-span' command; missing this would cause a different error, but the primary issue here is trunking.
- D
The destination port is not configured with 'monitor session' on the remote switch.
Why wrong: Incorrect because the destination port is configured, but the traffic must first be delivered via the RSPAN VLAN.
Quick Answer
The answer is that the RSPAN VLAN is not allowed on the trunk links between the switches. This is correct because RSPAN traffic must traverse the network infrastructure within a dedicated RSPAN VLAN, and if that VLAN is pruned or not explicitly permitted on the trunk ports connecting the source and destination switches, the monitored frames will be dropped at the trunk boundary. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your understanding of RSPAN VLAN propagation and the common misconfiguration of trunk allowed VLAN lists. A frequent trap is assuming that simply creating the RSPAN VLAN on both switches is sufficient, but the trunk must include it in the allowed list—often forgotten when using the `switchport trunk allowed vlan` command. Remember the memory tip: "RSPAN rides the rails—if the trunk doesn't carry the VLAN, the traffic derails."
300-410 SPAN, RSPAN, and ERSPAN Practice Question
This 300-410 practice question tests your understanding of span, rspan, and erspan. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
An engineer configures RSPAN on a Cisco switch to monitor traffic from VLAN 10 across multiple switches. The engineer creates an RSPAN VLAN (VLAN 100) on the source switch and configures the source as VLAN 10. On the remote switch, the engineer configures the destination port as GigabitEthernet0/1 in VLAN 100. However, the destination port does not forward any monitored traffic. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 RSPAN VLAN is not allowed on the trunk links between the switches.
RSPAN requires that the RSPAN VLAN be allowed on all trunk links between the source and destination switches. If the RSPAN VLAN is not allowed on the trunk, the traffic will not reach the destination.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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 RSPAN VLAN is not allowed on the trunk links between the switches.
- ✗
The destination port is configured as an access port in VLAN 100.
Why it's wrong here
Incorrect because the destination port should be in the RSPAN VLAN, but that alone does not cause the issue; the traffic must first reach the remote switch.
- ✗
The source switch does not have the RSPAN VLAN configured as a remote-span VLAN.
Why it's wrong here
Incorrect because the RSPAN VLAN is created with the 'remote-span' command; missing this would cause a different error, but the primary issue here is trunking.
- ✗
The destination port is not configured with 'monitor session' on the remote switch.
Why it's wrong here
Incorrect because the destination port is configured, but the traffic must first be delivered via the RSPAN VLAN.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Trap categories for this question
Command / output trap
Incorrect because the RSPAN VLAN is created with the 'remote-span' command; missing this would cause a different error, but the primary issue here is trunking.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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.
What to study next
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 300-410 questions on switching, trunking, and access-port configuration.
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SPAN, RSPAN, and ERSPAN — study guide chapter
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FAQ
Questions learners often ask
What does this 300-410 question test?
SPAN, RSPAN, and ERSPAN — This question tests SPAN, RSPAN, and ERSPAN — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The RSPAN VLAN is not allowed on the trunk links between the switches. — RSPAN requires that the RSPAN VLAN be allowed on all trunk links between the source and destination switches. If the RSPAN VLAN is not allowed on the trunk, the traffic will not reach the destination.
What should I do if I get this 300-410 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 300-410 questions on switching, trunking, and access-port configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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Last reviewed: Jun 19, 2026
This 300-410 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 300-410 exam.
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