The correct next step is to check the DNS configuration. Because the user can ping the gateway and access local resources, Layer 2 and Layer 3 connectivity on the local network is verified, meaning the issue is not with IP addressing or routing. The inability to reach the internet while local access works points directly to a name resolution failure—the browser cannot translate domain names to IP addresses without a properly configured DNS server. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to isolate network layers: a successful gateway ping rules out physical, data link, and network layer problems, leaving the application layer (DNS) as the prime suspect. A common trap is to immediately check the DHCP lease or default gateway again, but since the gateway is reachable, DNS is the logical next step. Memory tip: if you can ping IPs but not names, think “DNS is the missing link.”
N10-009 Network Troubleshooting Practice Question
This N10-009 practice question tests your understanding of network troubleshooting. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
After replacing a faulty network cable, a user reports that they can access local resources but not the internet. The technician verifies that the user's IP address is 192.168.1.100 with a subnet mask of 255.255.255.0 and a default gateway of 192.168.1.1. The technician can ping the default gateway successfully. Which of the following should the technician check NEXT?
Correct. DNS resolves domain names to IP addresses; if DNS is misconfigured, the user can reach IP addresses but not domain names. Since the gateway is reachable, DNS is the most likely next check.
B
B) DHCP server
Why wrong: The user already has an IP address (192.168.1.100), so the DHCP server is functioning. This is not the issue.
C
C) Router's firewall ACLs
Why wrong: While firewall ACLs could block internet traffic, the user can ping the gateway, so layer 3 connectivity exists. DNS is a more common cause and should be checked first.
D
D) Switch port VLAN assignment
Why wrong: If the VLAN were incorrect, the user would likely not have local connectivity. Since local resources are accessible, VLAN assignment is not the issue.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A) DNS configuration
The user can access local resources and successfully ping the default gateway, which confirms that Layer 2 and Layer 3 connectivity to the local network is working. The inability to access the internet while local access works points to a name resolution failure, as the browser relies on DNS to translate domain names to IP addresses. Checking DNS configuration is the logical next step because a misconfigured or missing DNS server would prevent internet access even when IP connectivity is intact.
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) DNS configuration
Why this is correct
Correct. DNS resolves domain names to IP addresses; if DNS is misconfigured, the user can reach IP addresses but not domain names. Since the gateway is reachable, DNS is the most likely next check.
Related concept
Read the scenario before looking for a memorised answer.
✗
B) DHCP server
Why it's wrong here
The user already has an IP address (192.168.1.100), so the DHCP server is functioning. This is not the issue.
✗
C) Router's firewall ACLs
Why it's wrong here
While firewall ACLs could block internet traffic, the user can ping the gateway, so layer 3 connectivity exists. DNS is a more common cause and should be checked first.
✗
D) Switch port VLAN assignment
Why it's wrong here
If the VLAN were incorrect, the user would likely not have local connectivity. Since local resources are accessible, VLAN assignment is not the issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume internet access failure must be a gateway or routing issue, but the successful ping to the default gateway proves Layer 3 connectivity is fine, forcing the focus to DNS as the most common cause of 'can't browse but can ping local.'
Detailed technical explanation
How to think about this question
DNS resolution uses UDP port 53 by default, and a misconfigured DNS server (e.g., pointing to an internal-only server or an unreachable public resolver) will cause 'Name Not Resolved' errors even when IP connectivity is perfect. The `nslookup` or `dig` command can quickly verify DNS functionality; if the user can ping an external IP like 8.8.8.8 but not a domain name, DNS is the culprit. In real-world scenarios, a faulty cable replacement might have jostled the NIC settings or the DHCP lease renewal could have cleared a manually set DNS server, leading to this exact symptom.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
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: A) DNS configuration — The user can access local resources and successfully ping the default gateway, which confirms that Layer 2 and Layer 3 connectivity to the local network is working. The inability to access the internet while local access works points to a name resolution failure, as the browser relies on DNS to translate domain names to IP addresses. Checking DNS configuration is the logical next step because a misconfigured or missing DNS server would prevent internet access even when IP connectivity is intact.
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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