This LFCS practice question tests your understanding of networking. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 (public IP 203.0.113.10/24) and eth1 (private IP 10.0.0.1/8). The default gateway is 203.0.113.1. The admin wants to ensure that traffic to the private subnet 10.0.0.0/8 goes via eth1. Which command correctly adds a static 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.
ip route add 10.0.0.1/8 dev eth1
Why wrong: This adds a host route, not network.
ip route add 10.0.0.0/8 via 10.0.0.1 dev eth0
Why wrong: Gateway is on wrong subnet, and dev should be eth1.
ip route add 10.0.0.0/8 dev eth1
Correct: adds network route via device eth1.
route add -net 10.0.0.0/8 eth1
Why wrong: The route command expects different syntax; this is deprecated and incorrect.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ip route add 10.0.0.0/8 dev eth1
Option C is correct because it adds a static route for the 10.0.0.0/8 network directly via the eth1 interface, which is the private interface with IP 10.0.0.1/8. The `ip route add` command with `dev eth1` specifies that traffic destined for the 10.0.0.0/8 subnet should be sent out through eth1, without needing a next-hop gateway since eth1 is directly connected to that subnet.
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.
ip route add 10.0.0.1/8 dev eth1
Why it's wrong here
This adds a host route, not network.
ip route add 10.0.0.0/8 via 10.0.0.1 dev eth0
Why it's wrong here
Gateway is on wrong subnet, and dev should be eth1.
ip route add 10.0.0.0/8 dev eth1
Why this is correct
Correct: adds network route via device eth1.
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.
route add -net 10.0.0.0/8 eth1
Why it's wrong here
The route command expects different syntax; this is deprecated and incorrect.
Common exam traps
The trap here is that candidates often confuse the network address with a host address (as in Option A) or incorrectly assume a gateway is always required (as in Option B), forgetting that directly connected networks only need a device specification.
Trap categories for this question
Command / output trap
The route command expects different syntax; this is deprecated and incorrect.
Detailed technical explanation
When adding a static route for a directly connected network, the `dev` keyword tells the kernel that the destination is reachable without a next-hop router, which is appropriate here because eth1 is on the 10.0.0.0/8 subnet. The `ip route` command uses the kernel's routing table (FIB) to make forwarding decisions, and a route with only a device (no gateway) is considered a 'directly connected' route, which is automatically added for interfaces with configured IP addresses but can also be manually added for additional subnets on the same link. In real-world scenarios, this is useful when multiple subnets share the same physical segment (e.g., VLANs) or when using interface aliases.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Networking — This question tests Networking — Read the scenario before looking for a memorised answer..
The correct answer is: ip route add 10.0.0.0/8 dev eth1 — Option C is correct because it adds a static route for the 10.0.0.0/8 network directly via the eth1 interface, which is the private interface with IP 10.0.0.1/8. The `ip route add` command with `dev eth1` specifies that traffic destined for the 10.0.0.0/8 subnet should be sent out through eth1, without needing a next-hop gateway since eth1 is directly connected to that subnet.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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.
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