N10-009 Question 290
Single answerA network technician is troubleshooting a report that users on the third floor cannot reach a newly installed internal web application, while users on other floors can access it normally. The technician has already identified a likely cause: the third-floor access switch may have the wrong VLAN assigned to several user ports after a recent reconfiguration. To test this theory, the technician checks one affected port and finds it is assigned to VLAN 30, but documentation shows third-floor users should be in VLAN 20. What should the technician do NEXT according to structured troubleshooting best practices?
- A
Reassign the affected ports to VLAN 20, verify connectivity to the application, and document the resolution if service is restored
- B
Immediately replace the access switch because the incorrect VLAN assignment confirms a hardware failure
- C
Ignore the VLAN mismatch and begin investigating DNS because application access issues are usually name resolution problems
- D
Escalate to the server team before making any changes, since the application itself may still be unavailable
- E
Reboot the core switch first to clear any stale VLAN information before changing the access port configuration
Show answer and explanation
Correct answer: A
Explanation
This question focuses on the Network+ troubleshooting step: test the theory to determine the cause, then if the theory is confirmed, determine the next steps to resolve the problem. In the scenario, the suspected cause was a VLAN misconfiguration, and testing confirmed the affected port is assigned to the wrong VLAN. According to widely accepted troubleshooting methodology, such as the CompTIA Network+ process and common vendor operational best practices, the technician should correct the confirmed issue, test functionality to ensure the problem is resolved, and document the outcome. If the theory had not been confirmed, the technician would need to establish a new theory or escalate as appropriate. The key distinction is that confirmed evidence should drive the next action rather than restarting the troubleshooting process or escalating too early.
- A. Correct.
Correct. The theory has been tested and confirmed: the affected port is in the wrong VLAN compared with network documentation. Following standard troubleshooting methodology, the next step is to implement the appropriate fix, verify full functionality, and document findings and resolution. In this scenario, moving the affected ports to VLAN 20 is the logical corrective action, followed by testing access to the web application.
- B. Incorrect.
Incorrect. An incorrect VLAN assignment indicates a configuration problem, not evidence of hardware failure. Replacing the switch would be premature and would skip the proper next step after confirming the theory. This option reflects the common mistake of jumping to hardware replacement before resolving a verified logical misconfiguration.
- C. Incorrect.
Incorrect. DNS could cause application reachability issues in some cases, but the technician has already confirmed a specific and relevant mismatch in VLAN assignment. Best practice is to act on the confirmed theory before pursuing a different one. Choosing this option would ignore the evidence gathered during testing.
- D. Incorrect.
Incorrect. Escalation is appropriate when the theory is not confirmed, when the issue is outside the technician's authority, or when additional expertise is required. Here, the technician has confirmed a likely cause within the access layer and can take the next corrective step directly. Escalating now would be unnecessary and inefficient.
- E. Incorrect.
Incorrect. Rebooting the core switch is not an appropriate first response to a confirmed access-port VLAN misconfiguration. VLAN membership on user access ports is typically controlled on the access switch port configuration, and rebooting upstream infrastructure would introduce unnecessary disruption without addressing the actual confirmed cause.