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SSCP Practice Question: A security analyst is troubleshooting a network…
A security analyst is troubleshooting a network issue where users on VLAN 10 cannot reach a server on VLAN 20. The router has an ACL applied to the interface connected to VLAN 10. Which step should the analyst take first to isolate the problem?
⚠ Common exam trap
ISC2 often tests the principle of starting with the most likely cause at the Layer 3/4 boundary (the ACL) rather than jumping to lower-layer troubleshooting like ARP or VLAN verification, which would be premature when an ACL is explicitly present.
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
✓
Review the ACL configuration on the router interface
The ACL applied to the router interface connected to VLAN 10 is the most likely cause of the connectivity issue, as it can explicitly permit or deny traffic from VLAN 10 to VLAN 20. Reviewing the ACL configuration first allows the analyst to quickly determine if the traffic is being blocked by a deny statement or missing permit entry, which is a common and immediate cause of such inter-VLAN routing failures. This step is the most efficient because it directly addresses the access control mechanism at the routing boundary.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Review the ACL configuration on the router interface
Why this is correct
The ACL on the router interface can block traffic between VLANs; this is the first logical step.
- ✗
Run a traceroute from a user machine to the server
Why it's wrong here
Traceroute is useful but should be done after checking ACLs.
- ✗
Check the ARP table for the server's MAC address
Why it's wrong here
ARP is used to resolve MAC addresses, not to troubleshoot ACL issues.
- ✗
Verify the VLAN configuration on the switch
Why it's wrong here
VLAN configuration is important but the router's ACL is more likely the issue given the symptom.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 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 SSCP exam.