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CCNA Network Infrastructure and Connectivity Practice Question
Drag and drop the following steps into the correct order to isolate and resolve interface CRC errors, duplex mismatches, and flapping on a Cisco IOS-XE switch.
⚠ Common exam trap
Candidates often jump to hardware replacement or configuration changes without first gathering data. Always start with 'show interface' statistics to pinpoint the issue before taking corrective action.
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
✓
Check interface statistics for CRC errors, runts, or giants; verify duplex and speed settings; replace faulty cables or transceivers; monitor interface to confirm resolution.
Start with checking statistics to identify issues, then verify duplex and cable, replace hardware if needed, and finally confirm resolution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Check interface statistics for CRC errors, runts, or giants; verify duplex and speed settings; replace faulty cables or transceivers; monitor interface to confirm resolution.
Why this is correct
Starting with interface statistics is essential because CRC errors, runts, and giants pinpoint whether the issue is on the physical medium or in the negotiated parameters. Verifying duplex and speed settings after gathering data ensures you only adjust configuration if the counters actually indicate a mismatch. Replacing faulty cables or transceivers should follow only after you have confirmed that the existing hardware is suspect, not as a random first step. Finally, monitoring the interface confirms the error counters stop increasing and that the resolution is sustainable.
- ✗
Replace the cable immediately; then check interface statistics; if errors persist, adjust duplex settings; finally, monitor the interface.
Why it's wrong here
Jumping straight to cable replacement assumes the physical medium is the culprit without any evidence, which can waste time and resources when the true cause is a duplex mismatch. Checking interface statistics afterward defeats the diagnostic purpose because you have already changed a variable, making it hard to correlate the initial error condition with its source. Adjusting duplex settings only if errors persist is also backwards: a duplex mismatch is a common cause of CRC errors and late collisions, so it should be verified early. Monitoring last is appropriate, but only after a proper sequence of diagnosis and remediation.
- ✗
Verify duplex and speed settings; then replace the cable; check interface statistics; finally, monitor the interface.
Why it's wrong here
Verifying duplex and speed settings before reviewing interface statistics puts configuration changes ahead of fault-finding, leading you to chase symptoms rather than evidence. Replacing a cable before checking stats is similarly premature, as CRC errors could stem from a duplex mismatch or transceiver failure rather than the cable itself. The correct order is to use interface counters to isolate the OSI Layer 1/Layer 2 fault first, then adjust negotiated parameters if the counters justify it. Checking statistics only after hardware changes makes it impossible to know what actually fixed the problem.
- ✗
Monitor the interface for errors; then replace the cable; if errors continue, adjust duplex settings; finally, check interface statistics.
Why it's wrong here
Monitoring first is counterproductive because monitoring is meant to validate an implemented fix, not to begin the troubleshooting process. Replacing the cable before running any diagnostics risks introducing new variables and may not address the underlying problem. Adjusting duplex settings before checking statistics is guesswork, since you have no data on whether errors are CRC, runts, or giants, each with different implications. Last, checking interface statistics after all changes makes it impossible to determine the original cause or verify the effect of each step.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Check interface statistics for CRC errors, runts, or giants; verify duplex and speed settings; replace faulty cables or transceivers; monitor interface to confirm resolution.Correct answer▾
Why this is correct
Starting with interface statistics is essential because CRC errors, runts, and giants pinpoint whether the issue is on the physical medium or in the negotiated parameters. Verifying duplex and speed settings after gathering data ensures you only adjust configuration if the counters actually indicate a mismatch. Replacing faulty cables or transceivers should follow only after you have confirmed that the existing hardware is suspect, not as a random first step. Finally, monitoring the interface confirms the error counters stop increasing and that the resolution is sustainable.
✗Replace the cable immediately; then check interface statistics; if errors persist, adjust duplex settings; finally, monitor the interface.Wrong answer — click to see why▾
Why this is wrong here
The step order is reversed; troubleshooting should start with data collection, not hardware replacement.
Why candidates choose this
Candidates might think hardware is the most common cause and jump to replacement first, but best practice is to gather evidence first.
✗Verify duplex and speed settings; then replace the cable; check interface statistics; finally, monitor the interface.Wrong answer — click to see why▾
Why this is wrong here
The order is illogical; you need to see the errors before adjusting settings, and replacing the cable before checking statistics may be unnecessary.
Why candidates choose this
Candidates might think verifying configuration is the first step, but statistics provide the evidence needed to guide further actions.
✗Monitor the interface for errors; then replace the cable; if errors continue, adjust duplex settings; finally, check interface statistics.Wrong answer — click to see why▾
Why this is wrong here
The sequence is reversed; monitoring is for verification after corrective actions, and statistics should be checked before making changes.
Why candidates choose this
Candidates might think monitoring is a good starting point, but it is a passive step that should follow active troubleshooting.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Related to this question
Learn chapter
DNS Resolution Process
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.
Key term
CRC
CRC (Cyclic Redundancy Check) is an error-detecting code used to detect accidental changes to raw data in digital networks.
About these practice questions
This 200-301 question is part of Courseiva's 1,389-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 →
Same concept, more angles
1 more way this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Drag and drop the following steps into the correct order to isolate CRC errors, duplex mismatches, and flapping on a Cisco IOS-XE interface.
medium- ✓ A.Enter configuration mode, enable debugs, monitor logs, analyze data, apply fixes and verify.
- B.Enable debugs, enter configuration mode, monitor logs, analyze data, apply fixes and verify.
- C.Monitor logs, enter configuration mode, enable debugs, analyze data, apply fixes and verify.
- D.Enter configuration mode, monitor logs, enable debugs, analyze data, apply fixes and verify.
Why A: First enter configuration mode, then enable debugs to capture errors, monitor logs, analyze the data, and finally apply fixes and verify.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco 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 200-301 exam.