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 connect to the internet by IP address but cannot access any websites by domain name. Which command-line tool should a technician use first to isolate the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
nslookup
The user can reach the internet by IP address but not by domain name, which indicates a DNS resolution failure. The `nslookup` command queries DNS servers directly to test name resolution, making it the correct first step to isolate whether the issue is with the DNS server, the client's DNS configuration, or a network path to the DNS server.
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.
✗
ping
Why it's wrong here
Ping tests connectivity to a host using IP addresses or hostnames, but it does not specifically test DNS resolution.
✓
nslookup
Why this is correct
Nslookup is designed to query DNS servers and can verify that domain names are being resolved correctly.
Clue confirmation
The clue words "first", "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
tracert
Why it's wrong here
Tracert traces the route packets take to a destination, but it does not directly test DNS resolution.
✗
netstat
Why it's wrong here
Netstat displays active connections and listening ports, not DNS resolution capabilities.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose `ping` first because it is the most familiar troubleshooting tool, but the symptom of working IP connectivity with failed domain resolution specifically points to DNS, making `nslookup` the targeted diagnostic command.
Detailed technical explanation
How to think about this question
`nslookup` sends a DNS query (typically over UDP port 53) to the configured resolver and displays the response, including the resolved IP address or an error like 'Non-existent domain' or 'server failed'. In real-world scenarios, a misconfigured DNS server, a firewall blocking UDP 53, or a stale DNS cache can cause this symptom, and `nslookup` helps pinpoint whether the issue is local (client-side) or remote (server-side).
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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: nslookup — The user can reach the internet by IP address but not by domain name, which indicates a DNS resolution failure. The `nslookup` command queries DNS servers directly to test name resolution, making it the correct first step to isolate whether the issue is with the DNS server, the client's DNS configuration, or a network path to the DNS server.
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: "first", "which command". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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