The answer is that the router is not performing NAT correctly. This is the most likely cause because the server can ping its local gateway at 192.168.1.1 but cannot reach 8.8.8.8, and a traceroute stops at the gateway, indicating that traffic is not being forwarded beyond the local subnet. Since internal network connections work and the default route is properly configured, the failure to translate the private 192.168.x.x address to a public IP via Network Address Translation is the core issue blocking internet access. On the CompTIA Linux+ XK0-005 exam, this scenario tests your ability to differentiate between local routing problems and NAT misconfiguration—a common trap is assuming the DNS or gateway is wrong when the real culprit is the router’s translation table. Remember the key clue: if you can ping the gateway but not an external IP, and traceroute dies at the gateway, think “NAT is flat.”
XK0-005 Troubleshooting Practice Question
This XK0-005 practice question tests your understanding of 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 system administrator is troubleshooting a network issue on a Linux server running CentOS 7. The server is unable to connect to the internet, but internal network connections work fine. The administrator checks the network configuration: the server has a static IP 192.168.1.100/24, default gateway 192.168.1.1, and DNS server 8.8.8.8. The administrator can ping the gateway but cannot ping 8.8.8.8. From the server, a traceroute to 8.8.8.8 stops at the gateway. The administrator also notices that the route table shows a default route via 192.168.1.1. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router is not performing NAT correctly
The server can ping the gateway (192.168.1.1) but cannot reach 8.8.8.8, and traceroute stops at the gateway. This indicates that the server’s default route is correctly configured and the gateway is reachable, but the router is not forwarding traffic beyond the local subnet. Since internal connections work, the most likely cause is that the router is not performing Network Address Translation (NAT) correctly, which is required to translate private IP addresses (192.168.x.x) to a public IP for internet access.
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.
✓
The router is not performing NAT correctly
Why this is correct
The traceroute stopping at the gateway suggests the router is not forwarding packets to the internet, likely due to NAT misconfiguration.
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.
✗
The DNS server is not responding
Why it's wrong here
Ping uses IP address, not DNS, so DNS is not the issue here.
✗
The default gateway is not reachable
Why it's wrong here
The administrator can ping the gateway, so it is reachable.
✗
The subnet mask is incorrectly configured
Why it's wrong here
If the subnet mask were wrong, internal connectivity would likely be affected.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think a reachable gateway and a default route guarantee internet connectivity, but they overlook the necessity of NAT for private-to-public IP translation in a typical SOHO or enterprise network.
Detailed technical explanation
How to think about this question
NAT (Network Address Translation) is typically performed by the router to map private RFC 1918 addresses (like 192.168.1.100) to a public IP when traffic leaves the local network. Without proper NAT, the router will drop packets destined for external IPs because it has no route back to the private source. A traceroute that stops at the gateway with no further hops is a classic symptom of a missing or misconfigured NAT rule, often seen when the router’s NAT overload (PAT) is disabled or the ACL blocking translation is applied.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The router is not performing NAT correctly — The server can ping the gateway (192.168.1.1) but cannot reach 8.8.8.8, and traceroute stops at the gateway. This indicates that the server’s default route is correctly configured and the gateway is reachable, but the router is not forwarding traffic beyond the local subnet. Since internal connections work, the most likely cause is that the router is not performing Network Address Translation (NAT) correctly, which is required to translate private IP addresses (192.168.x.x) to a public IP for internet access.
What should I do if I get this XK0-005 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.
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