hardMultiple ChoiceObjective-mapped
FC0-U71 Practice Question: A technician notices that a switch interface is…
A technician notices that a switch interface is showing many CRC errors. What is the most likely cause?
⚠ Common exam trap
The trap here is that candidates often associate CRC errors with duplex mismatch because both can appear under high-traffic conditions, but The FC0-U61 exam specifically tests that CRC errors point to physical-layer issues like cabling, while duplex mismatch manifests as late collisions and runts.
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
✓
Faulty cable
CRC errors indicate that frames received on the interface have failed the cyclic redundancy check, meaning the data has been corrupted during transmission. A faulty cable is the most common cause of such corruption because it can introduce electrical interference, signal degradation, or physical breaks that alter the bits in the frame. While duplex mismatch can cause CRC errors in some cases, a faulty cable is the primary suspect when CRC errors are present.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Duplex mismatch
Why it's wrong here
Duplex mismatch usually causes collisions and late collisions, not CRC errors.
- ✓
Faulty cable
Why this is correct
CRC errors are often due to damaged cables, poor connections, or electromagnetic interference.
- ✗
Incorrect IP configuration
Why it's wrong here
IP configuration errors do not cause CRC errors at the physical layer.
- ✗
MAC address flooding
Why it's wrong here
MAC flooding is a security exploit that fills the switch's MAC table, not a cause of CRC errors.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This FC0-U71 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 FC0-U71 exam.