This FC0-U61 practice question tests your understanding of infrastructure. 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 computer is unable to access the internet, but can access local network resources. 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.
Windows Firewall blocking outbound traffic
Why wrong: By default, Windows Firewall does not block outbound connections.
Incorrect default gateway
The default gateway is needed to route traffic outside the local subnet.
DNS server not responding
Why wrong: DNS failure would still allow IP-based internet access.
Faulty Ethernet cable
Why wrong: A faulty cable would likely prevent all network connectivity.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Incorrect default gateway
The default gateway is the router that connects a local subnet to other networks, including the internet. If the default gateway is incorrect, the computer can communicate within its own subnet (local resources) but cannot route packets to external networks, causing internet access to fail while local access remains functional.
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.
Windows Firewall blocking outbound traffic
Why it's wrong here
By default, Windows Firewall does not block outbound connections.
Incorrect default gateway
Why this is correct
The default gateway is needed to route traffic outside the local subnet.
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.
DNS server not responding
Why it's wrong here
DNS failure would still allow IP-based internet access.
Faulty Ethernet cable
Why it's wrong here
A faulty cable would likely prevent all network connectivity.
Common exam traps
The trap here is that candidates often confuse DNS resolution with internet connectivity, assuming that if DNS is down, the internet is inaccessible, but the question specifies 'unable to access the internet' (not just resolve names), and local access works, which points to a routing issue at the default gateway.
Detailed technical explanation
When a host sends a packet to a destination outside its subnet, it checks the destination IP against its own subnet mask. If the destination is not local, the host encapsulates the packet with the MAC address of the default gateway (obtained via ARP) and forwards it there. An incorrect default gateway IP or a missing gateway causes the packet to be sent to a non-router device or dropped, while local ARP-based communication remains unaffected. This behavior is defined in RFC 1122 and can be verified with the `route print` command on Windows or `ip route` on Linux.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
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FAQ
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Incorrect default gateway — The default gateway is the router that connects a local subnet to other networks, including the internet. If the default gateway is incorrect, the computer can communicate within its own subnet (local resources) but cannot route packets to external networks, causing internet access to fail while local access remains functional.
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 11, 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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