Quick Answer
The answer is to check DNS resolution with nslookup, verify the default gateway route with route -n, and confirm the network interface configuration with ip addr show. When a host cannot reach the internet but can ping the local gateway, the issue typically lies above Layer 3—DNS failures prevent name resolution, a missing default route (0.0.0.0/0) blocks traffic beyond the local subnet, or a misconfigured interface lacks a proper IP or netmask. On the CompTIA Linux+ XK0-005 exam, this scenario tests your ability to isolate whether the problem is routing, DNS, or interface-level, often appearing as a multi-select question where a common trap is to immediately blame the firewall or proxy. Remember the mnemonic “RID”—Route, Interface, DNS—to systematically rule out each layer before moving to advanced diagnostics.
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.
Which THREE steps should be taken when diagnosing a network connectivity issue where a host cannot reach the internet but can ping the local gateway? (Select three.)
Examine the routing table with route -n
Check default route configuration.
Review firewall rules with iptables -L
Firewall may block outbound traffic.
Check ARP cache for the gateway
Why wrong: If ping works, ARP is fine.
Run traceroute to a known external IP
Why wrong: May be useful later, but DNS and routing are more fundamental.
Check DNS resolution with nslookup
DNS issues can prevent internet access.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Examine the routing table with route -n
Option A is correct because the `route -n` command displays the kernel routing table without resolving hostnames, allowing you to verify whether a default gateway route (0.0.0.0/0) exists. If the host can ping the local gateway but not the internet, a missing or incorrect default route is a common cause, as traffic to external networks would have no path to forward.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Examine the routing table with route -n
Why this is correct
Check default route configuration.
Related concept
Read the scenario before looking for a memorised answer.
Review firewall rules with iptables -L
Why this is correct
Firewall may block outbound traffic.
Related concept
Read the scenario before looking for a memorised answer.
Check ARP cache for the gateway
Why it's wrong here
If ping works, ARP is fine.
Run traceroute to a known external IP
Why it's wrong here
May be useful later, but DNS and routing are more fundamental.
Check DNS resolution with nslookup
Why this is correct
DNS issues can prevent internet access.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates assume a successful ping to the gateway proves Layer 3 routing is fully functional, but they overlook that the host may lack a default route, which is a distinct routing table entry separate from gateway reachability.
Detailed technical explanation
The routing table uses the longest prefix match algorithm to determine the next hop for a destination; a default route (0.0.0.0/0) is the catch-all entry. If the default route is missing, packets destined for non-local networks are dropped at the host, even though the local gateway is reachable. In Linux, `route -n` shows the gateway column, and a missing entry for 0.0.0.0 with a netmask of 0.0.0.0 indicates no default gateway is configured.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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Troubleshooting — study guide chapter
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FAQ
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
The correct answer is: Examine the routing table with route -n — Option A is correct because the `route -n` command displays the kernel routing table without resolving hostnames, allowing you to verify whether a default gateway route (0.0.0.0/0) exists. If the host can ping the local gateway but not the internet, a missing or incorrect default route is a common cause, as traffic to external networks would have no path to forward.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This XK0-005 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 XK0-005 exam.
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