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. A key principle to apply: the hosts file is a local text file that maps hostnames to IP addresses.. 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 can access a website by its IP address (e.g., 203.0.113.5) but cannot access it by its domain name (example.com). Other users on the same subnet can access the website by domain name. Which of the following should the technician check FIRST?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A
The issue is isolated to a single user who can reach the website by IP but not by domain name, while other users on the same subnet have no problem. This points to a client-side DNS resolution failure, most likely a misconfigured or missing DNS server address in the user's network settings. The technician should first check the user's DNS configuration (e.g., `ipconfig /all` on Windows or `cat /etc/resolv.conf` on Linux) to ensure it points to a valid DNS server.
Key principle: The hosts file is a local text file that maps hostnames to IP addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
A
Why this is correct
A misconfigured hosts file on the local workstation can prevent successful DNS resolution for that machine.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
The hosts file is a local text file that maps hostnames to IP addresses.
✗
B
Why it's wrong here
The DNS server configuration is likely correct because other users on the same subnet can resolve the name.
✗
C
Why it's wrong here
The default gateway is used for routing, not DNS resolution, and connectivity is working (IP access works).
✗
D
Why it's wrong here
DHCP scope settings affect IP address assignment, not DNS resolution for specific names.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to checking the DNS server or website records globally, forgetting that the problem is isolated to one client, which clearly indicates a client-side configuration issue rather than a server or infrastructure problem.
Detailed technical explanation
How to think about this question
DNS resolution typically uses UDP port 53 for queries; if the client's configured DNS server is unreachable or incorrect, the resolver will fail to translate the domain name to an IP. A common subtlety is that a stale or incorrect DNS server entry in the client's network adapter properties (e.g., from a previous network or manual misconfiguration) can cause this exact symptom, while other devices on the same subnet use a different DNS server obtained via DHCP.
KKey Concepts to Remember
The hosts file is a local text file that maps hostnames to IP addresses.
The operating system checks the hosts file before querying DNS servers.
Incorrect entries in the hosts file can override correct DNS resolutions.
The hosts file is located at C:\Windows\System32\drivers\etc on Windows systems.
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
The hosts file is a local text file that maps hostnames to IP addresses.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
Review the hosts file is a local text file that maps hostnames to IP addresses., then practise related N10-009 questions on the same topic to reinforce the concept.
Network Troubleshooting — This question tests Network Troubleshooting — The hosts file is a local text file that maps hostnames to IP addresses..
What is the correct answer to this question?
The correct answer is: A — The issue is isolated to a single user who can reach the website by IP but not by domain name, while other users on the same subnet have no problem. This points to a client-side DNS resolution failure, most likely a misconfigured or missing DNS server address in the user's network settings. The technician should first check the user's DNS configuration (e.g., `ipconfig /all` on Windows or `cat /etc/resolv.conf` on Linux) to ensure it points to a valid DNS server.
What should I do if I get this N10-009 question wrong?
Review the hosts file is a local text file that maps hostnames to IP addresses., then practise related N10-009 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "first". 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?
The hosts file is a local text file that maps hostnames to IP addresses.
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