This LFCS practice question tests your understanding of networking. 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.
Exhibit
[user@server ~]$ ip route show
default via 10.0.0.1 dev eth0 proto static metric 100
10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.5 metric 100
10.0.1.0/24 via 10.0.0.2 dev eth0 proto static metric 100
192.168.1.0/24 dev eth1 proto kernel scope link src 192.168.1.10 metric 101
Refer to the exhibit. A server is configured with two network interfaces. A user on the 192.168.2.0/24 network reports that they cannot reach the server at IP 10.0.0.5. What is the most likely cause based on the routing table?
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.
[user@server ~]$ ip route show
default via 10.0.0.1 dev eth0 proto static metric 100
10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.5 metric 100
10.0.1.0/24 via 10.0.0.2 dev eth0 proto static metric 100
192.168.1.0/24 dev eth1 proto kernel scope link src 192.168.1.10 metric 101
A
There is no route on the server to the 192.168.2.0/24 network.
Without a return route, the server cannot send replies to the 192.168.2.0/24 network.
B
The default gateway is misconfigured; it should be 192.168.1.1.
Why wrong: The default gateway is correctly set to 10.0.0.1 for traffic on eth0.
C
The server's IP address 10.0.0.5 is not in the same subnet as the default gateway.
Why wrong: 10.0.0.5 is in the same subnet as 10.0.0.1 (10.0.0.0/24).
D
The firewall on eth0 is blocking incoming traffic.
Why wrong: There is no indication of firewall rules in the routing table.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
There is no route on the server to the 192.168.2.0/24 network.
The routing table on the server does not contain a route for the 192.168.2.0/24 network. When the user on that network sends traffic to 10.0.0.5, the server can receive it, but any reply traffic from the server to the 192.168.2.0/24 source address will be dropped because the server has no matching route. Without a route to the source network, the server cannot send return packets, making communication fail.
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.
✓
There is no route on the server to the 192.168.2.0/24 network.
Why this is correct
Without a return route, the server cannot send replies to the 192.168.2.0/24 network.
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 default gateway is misconfigured; it should be 192.168.1.1.
Why it's wrong here
The default gateway is correctly set to 10.0.0.1 for traffic on eth0.
✗
The server's IP address 10.0.0.5 is not in the same subnet as the default gateway.
Why it's wrong here
10.0.0.5 is in the same subnet as 10.0.0.1 (10.0.0.0/24).
✗
The firewall on eth0 is blocking incoming traffic.
Why it's wrong here
There is no indication of firewall rules in the routing table.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Linux Foundation often tests the misconception that a missing route only affects outbound traffic, but the trap here is that the server can receive packets from the 192.168.2.0/24 network but cannot reply, causing a one-way communication failure that users perceive as 'cannot reach the server'.
Detailed technical explanation
How to think about this question
In Linux, the routing table is consulted for outbound packets using the longest prefix match algorithm. If no specific route exists for the destination network, the default gateway (0.0.0.0/0) is used. However, in this scenario, the server's default gateway points to 192.168.1.1, which is on the 10.0.0.0/24 subnet, so return traffic to 192.168.2.0/24 would be sent to the default gateway—but if that gateway does not have a route back to 192.168.2.0/24, the packet is dropped. This is a classic asymmetric routing problem. The fix would be to add a static route via `ip route add 192.168.2.0/24 via <next-hop>` or ensure the default gateway can route to that network.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking — This question tests Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: There is no route on the server to the 192.168.2.0/24 network. — The routing table on the server does not contain a route for the 192.168.2.0/24 network. When the user on that network sends traffic to 10.0.0.5, the server can receive it, but any reply traffic from the server to the 192.168.2.0/24 source address will be dropped because the server has no matching route. Without a route to the source network, the server cannot send return packets, making communication fail.
What should I do if I get this LFCS 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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Question Discussion
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