N10-009 Network Troubleshooting Practice Question
A network technician is troubleshooting a connectivity issue between two switches. The technician suspects a duplex mismatch on the link between them. Which of the following commands would best confirm this suspicion?
⚠ Common exam trap
The trap here is assuming that show interface counters errors will directly indicate a duplex mismatch, when it only shows symptoms like late collisions, not the duplex configuration itself.
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
✓
show interfaces
The correct answer is show interfaces. This command displays the duplex and speed settings for each interface, allowing the technician to compare both ends of the link. A duplex mismatch occurs when one side is set to full-duplex and the other to half-duplex, leading to performance issues and errors. The other commands do not directly show duplex settings, making them less effective for confirming a duplex mismatch.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
show cdp neighbors
Why it's wrong here
This command displays information about directly connected Cisco devices, including platform and interface details. It does not show duplex settings, so it cannot confirm a duplex mismatch. It is useful for discovering topology but not for verifying duplex configuration.
- ✗
show mac address-table
Why it's wrong here
This command displays the MAC address table, mapping MAC addresses to switch ports. It is used for troubleshooting Layer 2 forwarding issues, such as MAC address flapping, but provides no information about duplex settings on a link.
- ✓
show interfaces
Why this is correct
The show interfaces command displays detailed information about each interface, including duplex and speed settings. By comparing the duplex configuration on both ends of the link, the technician can confirm if one side is set to full-duplex and the other to half-duplex, which is a duplex mismatch.
- ✗
show interface counters errors
Why it's wrong here
This command displays error statistics such as CRC errors, late collisions, and runts. While a duplex mismatch can cause some of these errors, it does not directly confirm duplex settings. It is more useful for identifying general link errors, but not specifically duplex mismatch.
Go deeper
Related to this question
Learn chapter
VLAN Mismatch and Native VLAN Issues
Key term
Duplex mismatch
A duplex mismatch occurs when two connected network devices are configured with different duplex settings (one half-duplex, one full-duplex), leading to poor performance and data errors.
Key term
Interface
An interface is a point of connection or interaction between two systems, devices, or software components that allows them to exchange information or signals.
About these practice questions
This N10-009 question is part of Courseiva's 472-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.