The correct interpretation is that the session is properly configured as an ERSPAN source session, as indicated by the Type field showing "ERSPAN Source Session" alongside a source port, destination IP, and ERSPAN ID. This output confirms that the router is configured to mirror traffic from GigabitEthernet0/0 and encapsulate it with an ERSPAN header, sending the mirrored packets to the destination IP 10.1.1.1 using ERSPAN ID 100 for session identification. On the Cisco CCNP ENARSI 300-410 exam, this command tests your ability to distinguish between source and destination ERSPAN configurations, a common pitfall where candidates confuse the two sides. A frequent trap is assuming the destination IP alone indicates a destination session, but the "Source Session" type and the presence of source ports are the definitive clues. Remember the memory tip: "Source shows ports, destination shows targets"—if you see source ports listed, you are looking at the source side of the ERSPAN mirror.
300-410 SPAN, RSPAN, and ERSPAN Practice Question
This 300-410 practice question tests your understanding of span, rspan, and erspan. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A network engineer runs the following command to troubleshoot an ERSPAN issue:
R1# show monitor session 3 detail
Session 3
---------
Type : ERSPAN Source Session
Source Ports :
Both : Gi0/0
Destination IP : 10.1.1.1
ERSPAN ID : 100
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The session is correctly configured as an ERSPAN source session.
The output shows an ERSPAN source session with source port Gi0/0, destination IP 10.1.1.1, and ERSPAN ID 100. This is the source side of an ERSPAN configuration.
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 session is correctly configured as an ERSPAN source session.
Why this is correct
The output confirms an ERSPAN source session with a destination IP and ERSPAN ID.
Related concept
Access ports place end devices into a single VLAN.
✗
The session is misconfigured because the destination must be a VLAN, not an IP.
Why it's wrong here
ERSPAN uses an IP address as the destination for remote monitoring.
✗
The session is misconfigured because the source port must be a VLAN.
Why it's wrong here
Source ports can be physical interfaces in ERSPAN.
✗
The session is misconfigured because the ERSPAN ID must match on both source and destination.
Why it's wrong here
The ERSPAN ID must match, but this output does not indicate a misconfiguration.
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
The ERSPAN ID must match, but this output does not indicate a misconfiguration.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
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.
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 session is correctly configured as an ERSPAN source session. — The output shows an ERSPAN source session with source port Gi0/0, destination IP 10.1.1.1, and ERSPAN ID 100. This is the source side of an ERSPAN configuration.
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.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network engineer runs the following command to troubleshoot an ERSPAN issue:
R1# show monitor session 5 detail
Session 5
---------
Type : ERSPAN Destination Session
Source IP : 10.1.1.2
ERSPAN ID : 100
Destination Ports : Gi0/3
Encapsulation : Native
Ingress : Disabled
What does this output indicate?
medium
✓ A.The session is correctly configured as an ERSPAN destination session.
B.The session is misconfigured because the source must be a VLAN, not an IP.
C.The session is misconfigured because the destination port must have ingress enabled.
D.The session is misconfigured because the ERSPAN ID must be different from the source session.
Why A: The output shows an ERSPAN destination session with source IP 10.1.1.2, ERSPAN ID 100, and destination port Gi0/3. This is the destination side of an ERSPAN configuration.
Variation 2. A network engineer runs the following command to troubleshoot an ERSPAN issue:
R1# show monitor session 6 detail
Session 6
---------
Type : ERSPAN Source Session
Source VLANs :
Both : 10-20
Destination IP : 10.1.1.3
ERSPAN ID : 200
What does this output indicate?
hard
✓ A.The session is correctly configured to monitor VLANs 10 through 20.
B.The session is misconfigured because ERSPAN cannot use VLANs as source.
C.The session is misconfigured because the ERSPAN ID must be less than 100.
D.The session is misconfigured because the destination IP must be on the same subnet.
Why A: The output shows an ERSPAN source session with source VLANs 10-20, destination IP 10.1.1.3, and ERSPAN ID 200. This is a valid ERSPAN source session using VLANs as the source.
Variation 3. A network engineer runs the following command to troubleshoot an ERSPAN issue:
R1# show ip interface brief | include Gi0/0
GigabitEthernet0/0 10.1.1.1 YES NVRAM up up
R1# show monitor session 7 detail
Session 7
---------
Type : ERSPAN Source Session
Source Ports :
Both : Gi0/1
Destination IP : 10.1.1.2
ERSPAN ID : 300
What does this output indicate?
hard
✓ A.The ERSPAN session is correctly configured and the destination IP is reachable.
B.The ERSPAN session is misconfigured because the source port must have an IP address.
C.The ERSPAN session is misconfigured because the destination IP must be on the same subnet as the source.
D.The ERSPAN session is misconfigured because the ERSPAN ID must be unique across all sessions.
Why A: The output shows that interface Gi0/0 has IP address 10.1.1.1 and is up/up, and ERSPAN session 7 has destination IP 10.1.1.2. This indicates that the ERSPAN source session is configured to send traffic to 10.1.1.2, which is reachable via Gi0/0.
Last reviewed: Jun 19, 2026
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