Quick Answer
The answer is a faulty network cable. When troubleshooting a single computer not connecting to the internet while other devices on the same network work fine, the issue is almost always isolated to the physical or logical connection of that specific device. A damaged or loose network cable can break the physical link between the computer and the switch or router, causing the network interface card to show a disconnected status or experience excessive packet loss, which prevents any data from reaching the internet. On the CompTIA ITF+ FC0-U61 exam, this scenario tests your ability to distinguish between problems affecting one device versus the entire network—a common trap is immediately blaming the router or ISP when the real culprit is a simple cable fault. Remember the memory tip: “One device down? Check the cable first.” This helps you avoid wasting time on complex configurations when the fix is often as straightforward as reseating or replacing the cable.
This FC0-U61 practice question tests your understanding of infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 computer is unable to connect to the internet, but other devices on the same network work fine. Which of the following is the MOST likely cause?
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.
Router firewall blocking traffic
Why wrong: Router firewall would block multiple devices.
DHCP server failure
Why wrong: DHCP failure would affect all devices.
DNS server misconfiguration
Why wrong: DNS issues affect name resolution, not all connectivity.
Faulty network cable
A faulty cable can cause connectivity loss for a single device.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Faulty network cable
A faulty network cable can prevent a single computer from connecting to the internet while other devices on the same network work fine. This is because the cable physically connects the computer to the network switch or router, and if it is damaged, the link may fail entirely or cause excessive packet loss, isolating only that device.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Router firewall blocking traffic
Why it's wrong here
Router firewall would block multiple devices.
DHCP server failure
Why it's wrong here
DHCP failure would affect all devices.
DNS server misconfiguration
Why it's wrong here
DNS issues affect name resolution, not all connectivity.
Faulty network cable
Why this is correct
A faulty cable can cause connectivity loss for a single device.
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.
Common exam traps
The trap here is that candidates often assume network issues are always logical (e.g., DNS or DHCP) and overlook the physical layer, but CompTIA tests the principle that a single-device failure with others working points to a local physical or configuration problem, not a shared infrastructure fault.
Detailed technical explanation
A faulty Ethernet cable can cause link negotiation failures, CRC errors, or intermittent connectivity at the physical layer (Layer 1). Tools like `ping` to the default gateway or checking the network adapter's link lights can help isolate the issue; a continuous ping with packet loss or no response often points to a physical layer problem. In real-world scenarios, bent pins, broken clips, or internal wire breaks (e.g., in a crossover or straight-through cable) are common culprits that affect only the connected device.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the FC0-U61 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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Faulty network cable — A faulty network cable can prevent a single computer from connecting to the internet while other devices on the same network work fine. This is because the cable physically connects the computer to the network switch or router, and if it is damaged, the link may fail entirely or cause excessive packet loss, isolating only that device.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This FC0-U61 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-U61 exam.
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