20+ practice questions focused on Diagnosing Problems — one of the most tested topics on the Cisco Certified Support Technician - Networking exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Diagnosing Problems PracticeRefer to the exhibit. A technician sees this status for a switch port. Which action should be taken first?
Explanation: An interface status of 'up/down' (where the physical layer is up but the line protocol is down) typically indicates a Layer 1/Layer 2 issue such as a keepalive mismatch, clocking issue, or encapsulation mismatch. However, a duplex mismatch usually results in an 'up/up' status with high error rates (CRC/runts), not a 'down' line protocol. The most common cause for 'up/down' on a switch port is a keepalive failure or a mismatch in encapsulation/framing.
A branch office router reports OSPF neighbor adjacency failures. Which THREE items should be verified to troubleshoot this issue?
Explanation: OSPF neighbor adjacency requires matching Area ID, Hello/Dead intervals, Authentication settings, and Subnet masks (for broadcast/point-to-point networks). The OSPF Process ID is locally significant and does not need to match between neighbors.
Which symptom is most indicative of a mismatched native VLAN on a trunk link between two Cisco switches?
Explanation: Cisco switches run CDP (Cisco Discovery Protocol), which detects native VLAN mismatches across trunk links and generates periodic syslog messages warning the administrator of the misconfiguration. Options A, C, and D are typically caused by physical layer issues, duplex mismatches, port security violations, or DHCP failures, not specifically a native VLAN mismatch.
During a network audit, a technician finds that an interface is frequently transitioning between up and down states. Which feature should be configured to prevent unnecessary STP topology changes?
Explanation: While PortFast moves a port to the forwarding state immediately, it is the combination of PortFast and the fact that the port does not generate TCNs (Topology Change Notifications) when the link state changes that prevents STP topology recalculations. The explanation should explicitly mention that PortFast prevents the port from generating TCNs upon link state transitions.
A technician is diagnosing an intermittent connectivity issue between two switches. Which TWO commands would be most useful for identifying physical layer errors on a specific interface? (Choose two.)
Explanation: To identify physical layer errors such as CRC errors, runts, giants, and framing errors, a technician must examine the interface statistics provided by the 'show interfaces' command. While 'show ip interface brief' is useful for a quick overview of interface status and IP addresses, it does not display error counters. (Note: Depending on the specific platform, 'show controllers' is also used for physical layer diagnostics, but among standard CCST-level options, 'show interfaces' is the primary choice. If only one command is primarily used for errors, the question or options may need adjustment, but assuming standard CCST scope, another operational command or specific syntax is often expected. However, let's correct option D to a better diagnostic command if applicable, or fix the error description).
+15 more Diagnosing Problems questions available
Practice all Diagnosing Problems questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Diagnosing Problems. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Diagnosing Problems questions on the 100-150 frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Diagnosing Problems is tested as part of the Cisco Certified Support Technician - Networking blueprint. Practicing with targeted Diagnosing Problems questions ensures you can handle any format or difficulty that appears.
Yes. Courseiva provides free 100-150 practice questions across all exam topics and domains. The platform includes topic-based practice, mock exams, missed-question review, bookmarked questions, and readiness tracking — no account required.
Difficulty is subjective, but Diagnosing Problems is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
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