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200-901 Practice Question: Is troubleshooting slow connectivity between two…
A network engineer is troubleshooting slow connectivity between two sites connected via a WAN link. The engineer suspects packet loss due to collisions. Which interface counter should be examined to confirm this?
⚠ Common exam trap
Cisco often tests the misconception that collisions are directly indicated by 'runts' or 'output errors', but the correct indicator for collision-induced corruption is the CRC errors counter, especially when the link is suspected of operating in half-duplex mode.
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
✓
CRC errors
CRC (Cyclic Redundancy Check) errors indicate that frames received on an interface have failed the integrity check, which is often caused by physical-layer issues such as collisions, faulty cabling, or signal degradation. In the context of a WAN link, collisions are not typical (since full-duplex is standard), but if the link is misconfigured as half-duplex, collisions can occur and will manifest as CRC errors. Thus, examining the CRC errors counter is the correct way to confirm packet loss due to collisions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Runts
Why it's wrong here
Runts are frames smaller than 64 bytes, not collision-specific.
- ✓
CRC errors
Why this is correct
CRC errors indicate frame checksum failures often caused by collisions.
- ✗
Output errors
Why it's wrong here
Output errors are a general category, not specific to collisions.
- ✗
Giants
Why it's wrong here
Giants are frames larger than maximum size, not collision-specific.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 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 200-901 exam.