- A
The DNS server is not reachable.
Why wrong: If DNS were unreachable, the user would likely fail to resolve internal and external hostnames, but they can access internal sites, possibly by IP. However, the scenario states they can access internal websites (using names?) and others work, so DNS is probably fine.
- B
The proxy server settings are incorrect.
Incorrect proxy settings (e.g., pointing to a non-existent or wrong proxy) would prevent external access while allowing internal access if the proxy is bypassed for internal addresses. This is a common client-specific issue.
- C
The default gateway is misconfigured.
Why wrong: If the default gateway were misconfigured, the user would likely not be able to reach any destinations outside their subnet, including internal websites on other subnets. They would also have no external access, but internal access works, so this is unlikely.
- D
The web browser has a corrupted cache.
Why wrong: A corrupted browser cache might cause errors on certain sites but would not completely prevent access to all external websites. It would also affect internal sites if they are cached.
Quick Answer
The answer is incorrect proxy server settings. This is the most likely cause because the user can access internal sites but not external ones, while other users on the same subnet have no issues, isolating the problem to a client-specific configuration rather than a network-wide fault like a broken gateway or DNS. In proxy misconfiguration troubleshooting, a device’s web browser or system proxy settings may be pointed to a server that cannot route external HTTP/HTTPS traffic, or the proxy itself may be unreachable, while internal traffic often bypasses the proxy entirely. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to differentiate between client-side and infrastructure faults; a common trap is to suspect DNS or the default gateway first, but the correct IP and subnet mask, plus other users working, rule those out. Remember the memory tip: “Internal works, external fails? Check the proxy trails.”
N10-009 Network Troubleshooting Practice Question
This N10-009 practice question tests your understanding of network troubleshooting. 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 they can access internal websites but cannot access any external websites. Other users in the same subnet can access external sites. The user's IP configuration shows a correct IP, subnet mask, and default gateway. What 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.
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 proxy server settings are incorrect.
The user can access internal websites but not external ones, while other users in the same subnet have no issues. This points to a client-specific configuration problem rather than a network-wide issue. Incorrect proxy server settings on the user's machine can prevent external HTTP/HTTPS traffic from being routed correctly, even though internal traffic (which may bypass the proxy) works fine.
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 DNS server is not reachable.
Why it's wrong here
If DNS were unreachable, the user would likely fail to resolve internal and external hostnames, but they can access internal sites, possibly by IP. However, the scenario states they can access internal websites (using names?) and others work, so DNS is probably fine.
- ✓
The proxy server settings are incorrect.
Why this is correct
Incorrect proxy settings (e.g., pointing to a non-existent or wrong proxy) would prevent external access while allowing internal access if the proxy is bypassed for internal addresses. This is a common client-specific issue.
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 default gateway is misconfigured.
Why it's wrong here
If the default gateway were misconfigured, the user would likely not be able to reach any destinations outside their subnet, including internal websites on other subnets. They would also have no external access, but internal access works, so this is unlikely.
- ✗
The web browser has a corrupted cache.
Why it's wrong here
A corrupted browser cache might cause errors on certain sites but would not completely prevent access to all external websites. It would also affect internal sites if they are cached.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between network-layer issues (like default gateway or DNS) and application-layer issues (like proxy configuration), leading candidates to incorrectly choose DNS or gateway problems when the symptom is isolated to a single user with correct IP settings.
Trap categories for this question
Scenario analysis trap
If DNS were unreachable, the user would likely fail to resolve internal and external hostnames, but they can access internal sites, possibly by IP. However, the scenario states they can access internal websites (using names?) and others work, so DNS is probably fine.
Detailed technical explanation
How to think about this question
Proxy servers act as intermediaries for client requests, often configured via PAC files, WPAD, or manual browser settings. If the proxy is incorrectly set (e.g., pointing to a non-existent server or requiring authentication), the client's browser may fail to establish outbound connections for external sites, while internal traffic might bypass the proxy via exception lists. This scenario is common in enterprise environments where proxy auto-configuration is used, and a misconfigured proxy can cause selective internet access failure.
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 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
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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Network Troubleshooting — study guide chapter
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Troubleshooting — This question tests Network Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The proxy server settings are incorrect. — The user can access internal websites but not external ones, while other users in the same subnet have no issues. This points to a client-specific configuration problem rather than a network-wide issue. Incorrect proxy server settings on the user's machine can prevent external HTTP/HTTPS traffic from being routed correctly, even though internal traffic (which may bypass the proxy) works fine.
What should I do if I get this N10-009 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: Jun 30, 2026
This N10-009 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 N10-009 exam.
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