hardMultiple ChoiceObjective-mapped
FC0-U71 Practice Question: After a network upgrade, a user reports that…
After a network upgrade, a user reports that their computer intermittently loses network connectivity. The link light remains on, but the activity light flashes rapidly and irregularly. What is the most likely cause?
⚠ Common exam trap
Watch out — candidates often confuse physical layer symptoms (bad cable) with Layer 2 or Layer 3 issues (IP conflict, driver corruption), assuming that intermittent connectivity must be a software or configuration problem rather than a hardware fault.
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
✓
Bad Ethernet cable
The intermittent connectivity with the link light on but the activity light flashing rapidly and irregularly is a classic symptom of a faulty or marginal Ethernet cable. A bad cable can cause excessive collisions or frame errors, leading to retransmissions that manifest as rapid, irregular activity light flashing while the physical link (link light) remains established. This is distinct from issues like IP conflicts or driver corruption, which typically do not produce this specific link/activity light behavior.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
IP address conflict
Why it's wrong here
An IP conflict would likely cause continuous disconnection or error messages.
- ✓
Bad Ethernet cable
Why this is correct
A bad cable can cause intermittent connectivity and rapid error flashes.
- ✗
Driver corruption
Why it's wrong here
Driver issues usually cause persistent problems, not intermittent with link light on.
- ✗
Faulty NIC
Why it's wrong here
A faulty NIC typically causes the link light to be off or intermittent, not on solid.
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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.