- A
The switch port is set to half-duplex
Why wrong: Half-duplex would cause collisions but not necessarily intermittent connection; the link light would still be steady or blink.
- B
The cable is damaged or has a loose connector
A damaged cable or loose connector can cause intermittent connectivity, leading to rapid link light blinking as the link drops and re-establishes.
- C
The network card is configured for 10 Mbps
Why wrong: A speed mismatch would cause no link or constant errors, not intermittent blinking; the link light would likely be off or solid.
- D
The switch is overloaded with traffic
Why wrong: Switch overload would cause slow performance, not intermittent connectivity; the link light would remain on.
Question 985 of 1,020
220-1201 Common Networking Hardware Practice Question
This 220-1201 practice question tests your understanding of common networking hardware. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that their wired connection is intermittent. They are using a Cat5e cable connected to a 1000BASE-T switch. The link light on the switch port is blinking rapidly. What is the most likely cause of the intermittent connection?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
✓
The cable is damaged or has a loose connector
A rapidly blinking link light typically indicates active data transmission, but when paired with an intermittent connection, it often points to physical-layer issues. A damaged Cat5e cable or loose connector can cause frequent link flaps and CRC errors, leading to the rapid blinking as the switch repeatedly attempts to re-establish the link. This is the most likely cause because the symptom (blinking link light) aligns with physical-layer problems rather than configuration or load issues.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The switch port is set to half-duplex
Why it's wrong here
Half-duplex would cause collisions but not necessarily intermittent connection; the link light would still be steady or blink.
- ✓
The cable is damaged or has a loose connector
Why this is correct
A damaged cable or loose connector can cause intermittent connectivity, leading to rapid link light blinking as the link drops and re-establishes.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The network card is configured for 10 Mbps
Why it's wrong here
A speed mismatch would cause no link or constant errors, not intermittent blinking; the link light would likely be off or solid.
- ✗
The switch is overloaded with traffic
Why it's wrong here
Switch overload would cause slow performance, not intermittent connectivity; the link light would remain on.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often associate a blinking link light with traffic activity, but in this context, the rapid blinking indicates link flapping due to physical-layer issues, not normal data transmission.
Detailed technical explanation
How to think about this question
In 1000BASE-T (802.3ab), the link light behavior is tied to the autonegotiation and link pulse process; a rapid blink often means the port is cycling through link detection due to intermittent electrical continuity. Damaged cables can introduce impedance mismatches or crosstalk, causing the PHY to lose synchronization and re-initiate the link training sequence, which manifests as a blinking LED. Real-world scenarios include bent pins in an RJ45 connector or a cable run near fluorescent lighting that induces noise, triggering frequent link drops.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Common Networking Hardware — study guide chapter
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Common Networking Hardware — This question tests Common Networking Hardware — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The cable is damaged or has a loose connector — A rapidly blinking link light typically indicates active data transmission, but when paired with an intermittent connection, it often points to physical-layer issues. A damaged Cat5e cable or loose connector can cause frequent link flaps and CRC errors, leading to the rapid blinking as the switch repeatedly attempts to re-establish the link. This is the most likely cause because the symptom (blinking link light) aligns with physical-layer problems rather than configuration or load issues.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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