N10-009 Question 296
Single answerVerify full system functionality and implement preventive measures if applicableA network technician replaced a failed access switch in a small branch office after hours. The new switch has been configured with the correct VLANs and trunk settings, and users can now reach internal file shares. The next morning, however, several employees report that they can browse internal resources but cannot make VoIP calls, obtain new DHCP leases after reconnecting their laptops, or print to a network printer in another VLAN. Which action should the technician take NEXT to verify full system functionality and help prevent a similar issue during future switch replacements?
- A
Perform end-to-end testing for voice, DHCP, and inter-VLAN services, then compare the new switch configuration against the saved baseline and update the replacement checklist
- B
Replace all user patch cables connected to the switch, because damaged cables commonly affect only VoIP, DHCP renewal, and printing traffic
- C
Increase the switch port speed on all access ports to 10 Gbps so latency-sensitive applications such as VoIP and printing can traverse VLANs correctly
- D
Reboot the DHCP server and call manager so they can detect the new switch and automatically rebuild their VLAN associations
Show answer and explanation
Correct answer: A
Explanation
The key concept is that verifying full system functionality requires more than confirming one successful service such as file-share access. After replacing network infrastructure, a technician should validate all critical business functions affected by the change, including voice, DHCP, printing, authentication, and inter-VLAN communication where applicable. In real environments, a switch replacement can restore basic connectivity while still missing important settings such as voice VLAN configuration, trunk allowed VLAN lists, QoS trust settings, STP edge settings, ACLs, or uplink parameters. Best practice is to compare the running configuration to a documented baseline or gold standard, perform post-change validation testing, and update checklists or standard operating procedures to prevent recurrence. These practices align with common network change-management and validation guidance from enterprise operational best practices and vendor switch deployment documentation.
- A. Correct.
This is the best next step because the issue indicates partial connectivity rather than complete failure. After a network change, verifying full system functionality means testing all affected services, not just basic file-share access. In this scenario, VoIP, DHCP relay/pathing, and printer access across VLANs should be validated end-to-end. Comparing the active configuration to a known-good baseline can reveal missing settings such as voice VLAN assignments, helper-address reachability, QoS trust boundaries, ACLs, or trunk-allowed VLAN mismatches. Updating the replacement checklist is also a preventive measure that reduces repeat incidents during future hardware swaps.
- B. Incorrect.
This is incorrect because bad patch cables typically cause link instability, errors, or total loss of connectivity on specific devices or ports, not a selective failure pattern affecting multiple services across VLANs while internal file access still works. A technician might pick this option because cabling is a common first troubleshooting step, but it does not align well with the symptoms described.
- C. Incorrect.
This is incorrect because port speed does not fix missing or incorrect logical configuration such as VLAN membership, trunking, DHCP relay reachability, or voice VLAN settings. Most branch-office endpoints such as phones, printers, and laptops do not require 10 Gbps, and increasing speed would not restore inter-VLAN functionality. This distractor reflects the misconception that performance settings can solve segmentation or control-plane issues.
- D. Incorrect.
This is incorrect because DHCP servers and call managers do not normally need to be rebooted after an access switch replacement in order to 'detect' the switch or rebuild VLAN mappings. VLAN configuration exists on the network infrastructure, and service reachability depends on correct switching and routing configuration. Someone might choose this option if they assume servers dynamically learn Layer 2 topology in a way that affects VLAN operation, but that is not how these services typically function.