The answer is a corrupt DNS cache on the user’s workstation. This is correct because the user can reach the intranet by IP address but not by hostname, which isolates the failure to the name resolution process. Since the DNS server holds a valid A record and returns the correct IP, the problem must be on the client side, where a corrupted cache stores stale or invalid data that overrides the server’s response. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to differentiate between server-side and client-side DNS failures—a common trap is to assume the DNS server is misconfigured when the real issue is local caching. Remember that flushing the cache with `ipconfig /flushdns` clears the corruption and restores proper resolution. Memory tip: think “IP works, name fails—flush the client’s stale 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 the company's intranet website by IP address but not by its hostname (intranet.company.local). A technician checks the DNS server and finds that the A record exists and returns the correct IP. However, the user's browser still cannot resolve the hostname. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The DNS cache on the user's workstation is corrupt.
The user can access the intranet by IP but not by hostname, which indicates that name resolution is failing. Since the DNS server has the correct A record, the issue is likely on the client side. A corrupt DNS cache on the workstation can cause the browser to use stale or invalid cached data, preventing successful resolution even though the authoritative DNS server returns the correct IP. Flushing the DNS cache with `ipconfig /flushdns` would resolve this.
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 cache on the user's workstation is corrupt.
Why this is correct
A corrupt DNS cache can cause incorrect or failed name resolution locally, even if the server record is correct.
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 web server's certificate is expired.
Why it's wrong here
An expired certificate would cause a security warning but not prevent hostname resolution; the user could still access by IP.
✗
The default gateway is misconfigured.
Why it's wrong here
If the default gateway were misconfigured, the user would not be able to access external or internal resources by IP either.
✗
The file server is overloaded.
Why it's wrong here
Server overload would affect performance regardless of name resolution, but not cause hostname-specific failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between server-side DNS configuration and client-side caching; the trap here is that candidates see 'A record exists and returns correct IP' and assume the DNS is fully functional, overlooking the client's local cache as the source of the problem.
Detailed technical explanation
How to think about this question
The DNS client on Windows maintains a local cache that stores recent query results, including negative responses (NXDOMAIN). If a previous query for 'intranet.company.local' returned a failure or a stale IP, the client will use that cached result instead of querying the DNS server again, even if the server now has a valid A record. This behavior is defined in RFC 1035 and implemented via the `dnscache` service; the `ipconfig /displaydns` command can reveal cached entries. In real-world scenarios, this often occurs after a DNS record update or a temporary server outage.
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 N10-009 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
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 DNS cache on the user's workstation is corrupt. — The user can access the intranet by IP but not by hostname, which indicates that name resolution is failing. Since the DNS server has the correct A record, the issue is likely on the client side. A corrupt DNS cache on the workstation can cause the browser to use stale or invalid cached data, preventing successful resolution even though the authoritative DNS server returns the correct IP. Flushing the DNS cache with `ipconfig /flushdns` would resolve this.
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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