The answer is the file server’s host firewall blocking ICMP. This is correct because the workstation can ping the default gateway but cannot ping the file server on the same subnet, which means the issue isn’t with IP configuration, ARP resolution, or the gateway—since both devices share the same subnet (192.168.1.0/24), traffic never leaves the local network and ARP should succeed. The most likely cause is that the file server’s firewall is configured to drop ICMP echo requests, preventing the ping from reaching the server or the reply from returning. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding that a successful ping to the gateway but failure to a local host points to a host-level restriction, not a network or routing problem—a common trap is assuming the gateway is needed for local traffic. Remember the memory tip: “Gateway good, server bad? Check the host’s firewall, not the router.”
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. A key principle to apply: a powered-off device cannot respond to network requests.. 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 cannot connect to a file server on the same subnet. The technician checks the workstation's IP configuration: IP 192.168.1.10, subnet mask 255.255.255.0, default gateway 192.168.1.1. The workstation can ping the gateway but cannot ping the file server at 192.168.1.50. 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.
Why wrong: A firewall blocking ICMP would prevent ping but might still allow SMB traffic for file access. Since the user cannot access files, this is less likely.
B
B
Why wrong: The default gateway is correctly configured because the workstation can ping it.
C
C
The server being powered off or having its network cable disconnected would cause all traffic to fail, matching the symptoms.
D
D
Why wrong: A subnet mask of 255.255.255.0 is correct for a /24 network and would not prevent communication with a server on the same subnet.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
C
The workstation can ping the gateway (192.168.1.1) but not the file server (192.168.1.50) on the same subnet. Since both are on the same subnet (192.168.1.0/24), the default gateway is irrelevant for local traffic; ARP is used to resolve the server's IP to its MAC address. The most likely cause is that the file server's firewall is blocking ICMP (ping) traffic, preventing the echo request from reaching the server or the reply from being sent.
Key principle: A powered-off device cannot respond to network requests.
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 it's wrong here
A firewall blocking ICMP would prevent ping but might still allow SMB traffic for file access. Since the user cannot access files, this is less likely.
✗
B
Why it's wrong here
The default gateway is correctly configured because the workstation can ping it.
✓
C
Why this is correct
The server being powered off or having its network cable disconnected would cause all traffic to fail, matching the symptoms.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
A powered-off device cannot respond to network requests.
✗
D
Why it's wrong here
A subnet mask of 255.255.255.0 is correct for a /24 network and would not prevent communication with a server on the same subnet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a failed ping means a network connectivity issue, but CompTIA often tests that a host firewall can block ICMP while allowing other traffic, so a ping failure does not necessarily indicate a broken path.
Detailed technical explanation
How to think about this question
On the same subnet, hosts use ARP to map an IP address to a MAC address before sending frames. If the file server's firewall blocks ICMP Echo Requests (type 8), the server will not respond with an Echo Reply (type 0), causing a ping failure even though other services (e.g., SMB on TCP 445) may still work. This is a common security practice to reduce attack surface while allowing application traffic.
KKey Concepts to Remember
A powered-off device cannot respond to network requests.
A disconnected network cable isolates a device from the network.
ICMP (ping) failure to a local device often indicates the device is offline or unreachable.
Successful ping to the default gateway confirms local network connectivity for the client.
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
A powered-off device cannot respond to network requests.
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.
Network Troubleshooting — This question tests Network Troubleshooting — A powered-off device cannot respond to network requests..
What is the correct answer to this question?
The correct answer is: C — The workstation can ping the gateway (192.168.1.1) but not the file server (192.168.1.50) on the same subnet. Since both are on the same subnet (192.168.1.0/24), the default gateway is irrelevant for local traffic; ARP is used to resolve the server's IP to its MAC address. The most likely cause is that the file server's firewall is blocking ICMP (ping) traffic, preventing the echo request from reaching the server or the reply from being sent.
What should I do if I get this N10-009 question wrong?
Review a powered-off device cannot respond to network requests., 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: "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?
A powered-off device cannot respond to network requests.
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