This LFCS practice question tests your understanding of networking. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 server has two network interfaces: eth0 (192.168.1.10/24) and eth1 (10.0.0.10/24). The default gateway is 192.168.1.1. The administrator wants traffic to 10.0.1.0/24 to go through eth1's gateway 10.0.0.1. Which command adds this route?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Both A and B are correct
Option A is correct because both B and C are valid `ip route add` syntax variations that achieve the same result: adding a route to 10.0.1.0/24 via gateway 10.0.0.1 on interface eth1. The `ip route` command accepts the `via` and `dev` keywords in either order, making both B and C syntactically correct. Option D uses the legacy `route` command with improper syntax (missing `dev` keyword before the interface name), which would fail or produce unexpected behavior.
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.
✓
Both A and B are correct
Why this is correct
Both commands correctly add the route; ip route is the modern method, but route is still supported on many systems.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
ip route add 10.0.1.0/24 via 10.0.0.1 dev eth1
Why it's wrong here
This command is correct, but option D is also correct. Since D includes both A and B, D is the best answer.
✗
ip route add 10.0.1.0/24 dev eth1 via 10.0.0.1
Why it's wrong here
The syntax is incorrect; 'via' should come before 'dev'.
This command is also correct, but D includes both.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the legacy `route` command's syntax is interchangeable with `ip route`, or that the order of `via` and `dev` in `ip route` is fixed, leading them to incorrectly dismiss valid options B or C.
Trap categories for this question
Command / output trap
This command is correct, but option D is also correct. Since D includes both A and B, D is the best answer.
Detailed technical explanation
How to think about this question
The `ip route` command from the iproute2 suite uses a flexible, keyword-based syntax where the order of `via` and `dev` is not strictly enforced, unlike the legacy `route` command which requires a fixed positional syntax. Under the hood, both commands modify the kernel's routing table (RTNETLINK), but `ip route` provides more granular control, such as adding multiple next hops or specifying metrics. In real-world scenarios, using `ip route` is preferred for scripting and automation due to its consistent parsing and JSON output support.
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: Both A and B are correct — Option A is correct because both B and C are valid `ip route add` syntax variations that achieve the same result: adding a route to 10.0.1.0/24 via gateway 10.0.0.1 on interface eth1. The `ip route` command accepts the `via` and `dev` keywords in either order, making both B and C syntactically correct. Option D uses the legacy `route` command with improper syntax (missing `dev` keyword before the interface name), which would fail or produce unexpected behavior.
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: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.
Question Discussion
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