The answer is a missing default route on the router. This is correct because when a ping to the default gateway succeeds but a ping to a public IP like 8.8.8.8 fails, it proves Layer 2 and local Layer 3 connectivity are intact, yet traffic cannot leave the local subnet. The router knows how to reach the gateway’s interface but lacks a default route (0.0.0.0/0) to forward packets beyond that network, so the packets are dropped at the router rather than being sent upstream. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to distinguish between local and remote connectivity failures—a common trap is assuming the issue is a firewall block, but the logs confirm ICMP is permitted, narrowing the cause to routing. Remember the mnemonic: “Local works, remote fails? Check the route that never fails—the default.”
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 cannot access the internet. The technician tests connectivity: pinging the default gateway succeeds, but pinging a public IP address like 8.8.8.8 fails. Firewall logs show outbound ICMP to 8.8.8.8 is permitted. What 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: DNS is used for name resolution; pinging by IP address does not require DNS.
B
Missing default route on the router
A missing default route means the router does not know where to send packets destined for external networks, causing failure to reach public IPs.
C
Duplicate IP address on the local network
Why wrong: A duplicate IP would cause intermittent connectivity issues but would still typically allow pinging the gateway; the symptoms described point to a routing issue.
D
Proxy server configuration is required
Why wrong: Proxy servers are used for application-layer traffic (HTTP/HTTPS), not for ICMP ping; ping does not go through a proxy.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Missing default route on the router
The user can ping the default gateway (local connectivity) but cannot ping a public IP like 8.8.8.8. This indicates that the workstation has a valid route to its local subnet, but the router lacks a default route (0.0.0.0/0) to forward traffic to the internet. Firewall logs confirm outbound ICMP is permitted, so the issue is at Layer 3 routing, not filtering.
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.
✗
Incorrect DNS configuration on the workstation
Why it's wrong here
DNS is used for name resolution; pinging by IP address does not require DNS.
✓
Missing default route on the router
Why this is correct
A missing default route means the router does not know where to send packets destined for external networks, causing failure to reach public IPs.
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.
✗
Duplicate IP address on the local network
Why it's wrong here
A duplicate IP would cause intermittent connectivity issues but would still typically allow pinging the gateway; the symptoms described point to a routing issue.
✗
Proxy server configuration is required
Why it's wrong here
Proxy servers are used for application-layer traffic (HTTP/HTTPS), not for ICMP ping; ping does not go through a proxy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between local connectivity (gateway reachable) and internet connectivity (default route missing), trapping candidates who assume DNS or firewall issues when the symptom is a successful ping to the gateway but failure to external IPs.
Detailed technical explanation
How to think about this question
A default route (0.0.0.0/0) is the catch-all entry in the routing table that directs packets destined for any network not explicitly listed. Without it, the router drops packets for external IPs, even though the workstation can reach the gateway. In real-world scenarios, this often occurs after a router misconfiguration or a BGP session failure that withdraws the default route.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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: Missing default route on the router — The user can ping the default gateway (local connectivity) but cannot ping a public IP like 8.8.8.8. This indicates that the workstation has a valid route to its local subnet, but the router lacks a default route (0.0.0.0/0) to forward traffic to the internet. Firewall logs confirm outbound ICMP is permitted, so the issue is at Layer 3 routing, not filtering.
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.
About these practice questions
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A user reports that they cannot access the internet. The technician verifies the workstation has IP address 192.168.1.10 with subnet mask 255.255.255.0 and default gateway 192.168.1.1. The user can ping the default gateway successfully. Other users on the same subnet can access the internet. Which command should the technician run on the workstation to further isolate the issue?
medium
A.ipconfig /all
✓ B.netstat -r
C.tracert 8.8.8.8
D.nslookup google.com
Why B: The user can ping the default gateway (192.168.1.1), indicating Layer 2 and basic Layer 3 connectivity to the local router. However, other users on the same subnet can access the internet, so the issue is likely with the workstation's routing table. The 'netstat -r' command displays the IP routing table, allowing the technician to check for a missing or incorrect default route (e.g., destination 0.0.0.0 with gateway 192.168.1.1). This isolates whether the workstation knows how to forward traffic beyond the local subnet.
Variation 2. A user reports that they cannot access the internet. The technician is able to ping the default gateway successfully but unable to ping a public IP address (e.g., 8.8.8.8). Which of the following is the most likely cause?
easy
A.Incorrect DNS server configuration
✓ B.The router's default route is missing or misconfigured
C.Duplicate IP address on the network
D.Faulty network interface card
Why B: Successful ping to the default gateway confirms Layer 2 and Layer 3 connectivity within the local subnet, but failure to ping a public IP like 8.8.8.8 indicates that traffic cannot leave the local network. This is most commonly caused by a missing or misconfigured default route on the router, which prevents the router from forwarding packets destined for external networks to the next-hop ISP gateway.
Last reviewed: Jun 30, 2026
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This N10-009 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the N10-009 exam.
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