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 Linux server with the IP address 192.168.1.100 is unable to communicate with other hosts on the same subnet 192.168.1.0/24. The administrator can ping the loopback address, but pinging 192.168.1.1 (the default gateway) fails. The output of `ip a` shows the eth0 interface has the correct IP and netmask. Which troubleshooting step should be performed next?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check the routing table with ip route.
Since the server has the correct IP and netmask on eth0 but cannot ping the default gateway (192.168.1.1), the issue likely lies in the routing configuration. The `ip route` command displays the kernel routing table, including the default gateway entry; if the default route is missing or incorrect, traffic cannot reach the gateway. Checking the routing table is the logical next step before assuming physical or ARP-level problems.
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.
✗
Check the ARP cache with arp -a.
Why it's wrong here
ARP may show incomplete entries but does not address routing configuration.
✗
Replace the network cable.
Why it's wrong here
The interface is up with correct IP, so cable is likely fine.
✗
Restart the network service.
Why it's wrong here
Restarting may not fix a missing route; verification of routing is more direct.
✓
Check the routing table with ip route.
Why this is correct
The routing table will show if a default gateway is configured; missing gateway causes failure to reach local gateway.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that a correct IP and netmask guarantee connectivity, leading candidates to jump to ARP or physical-layer checks, when the real issue is a missing or incorrect default route in the routing table.
Trap categories for this question
Command / output trap
ARP may show incomplete entries but does not address routing configuration.
Detailed technical explanation
How to think about this question
The Linux kernel uses the FIB (Forwarding Information Base) to determine the next hop for outbound packets; `ip route` queries this table. A missing default route (e.g., `default via 192.168.1.1 dev eth0`) would cause all off-subnet traffic to fail, while on-subnet communication might still work. In real-world scenarios, misconfigured static routes or missing gateway entries from DHCP are common causes of this 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 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.
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: Check the routing table with ip route. — Since the server has the correct IP and netmask on eth0 but cannot ping the default gateway (192.168.1.1), the issue likely lies in the routing configuration. The `ip route` command displays the kernel routing table, including the default gateway entry; if the default route is missing or incorrect, traffic cannot reach the gateway. Checking the routing table is the logical next step before assuming physical or ARP-level problems.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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