- A
A) Check the routing tables on the branch router
Correct. The branch router may not have a route to the file server's subnet, or the main office router may not have a route back to the branch subnet. Verifying routing tables on both ends is essential.
- B
B) Check the DNS resolution for the file server
Why wrong: Incorrect. The user can ping the gateway, so IP connectivity exists. If the user is pinging by IP, DNS is not involved. If by name, DNS failure would cause a different error.
- C
C) Check the VPN encryption settings
Why wrong: Incorrect. Since the VPN tunnel is active and the user can ping the remote gateway, the encryption settings are likely correct for the tunnel. A mismatch would prevent any traffic through the tunnel.
- D
D) Check the file server's antivirus software
Why wrong: Incorrect. Antivirus software on the file server could block certain traffic, but it would not cause a 'cannot connect' issue at the network level if routing is correct. It is less likely to be the first step.
Quick Answer
The answer is to check the routing tables on the branch router. While the VPN tunnel is active and the user can ping the main office’s default gateway—confirming Layer 3 connectivity across the tunnel—the inability to reach the file server means the branch router lacks a specific route for the file server’s subnet. Without that route, traffic destined for the file server may be dropped or sent out the wrong interface, even though the tunnel itself is up. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding that a tunnel being active does not guarantee end-to-end reachability; routing tables must explicitly direct traffic into the tunnel interface. A common trap is to assume the problem lies with the tunnel or firewall, but the ping to the gateway isolates the issue to routing. Memory tip: “Tunnel up, gateway ping—check the route for the server thing.”
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 at a branch office reports that they cannot connect to a file server at the main office. The branch office connects to the main office via a site-to-site VPN, and the VPN tunnel shows as active. The user can ping the main office's default gateway but not the file server. Which of the following should the technician check NEXT?
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
A) Check the routing tables on the branch router
The VPN tunnel is active and the user can ping the main office's default gateway, which confirms that Layer 3 connectivity exists across the tunnel. However, the file server is unreachable, indicating that the traffic destined for the file server's subnet is not being forwarded correctly. The next logical step is to check the routing tables on the branch router to ensure there is a specific route (or a default route) pointing to the VPN tunnel interface for the file server's network. Without this route, the branch router may be dropping the packets or sending them out the wrong interface.
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.
- ✓
A) Check the routing tables on the branch router
Why this is correct
Correct. The branch router may not have a route to the file server's subnet, or the main office router may not have a route back to the branch subnet. Verifying routing tables on both ends is essential.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
B) Check the DNS resolution for the file server
- ✗
C) Check the VPN encryption settings
- ✗
D) Check the file server's antivirus software
Why it's wrong here
Incorrect. Antivirus software on the file server could block certain traffic, but it would not cause a 'cannot connect' issue at the network level if routing is correct. It is less likely to be the first step.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a 'tunnel up' status guarantees end-to-end connectivity, but the trap here is that routing misconfiguration can allow the tunnel to be established while specific subnets remain unreachable.
Detailed technical explanation
How to think about this question
In a site-to-site VPN, the tunnel is a virtual interface (e.g., a VTI or GRE over IPsec) that requires explicit static or dynamic routes to direct traffic into it. Even if the tunnel is up, the branch router's routing table must contain a route for the file server's subnet (e.g., 192.168.2.0/24) pointing to the tunnel interface; otherwise, packets are forwarded out the WAN interface or dropped. A common real-world scenario is when a network administrator configures the VPN tunnel but forgets to add the necessary route statement, leading to a 'tunnel up, no traffic' issue that is easily diagnosed with 'show ip route' or 'traceroute'.
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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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: A) Check the routing tables on the branch router — The VPN tunnel is active and the user can ping the main office's default gateway, which confirms that Layer 3 connectivity exists across the tunnel. However, the file server is unreachable, indicating that the traffic destined for the file server's subnet is not being forwarded correctly. The next logical step is to check the routing tables on the branch router to ensure there is a specific route (or a default route) pointing to the VPN tunnel interface for the file server's network. Without this route, the branch router may be dropping the packets or sending them out the wrong interface.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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Last reviewed: Jun 11, 2026
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