LFCS Networking Practice Question
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?
⚠ Common exam trap
Candidates often 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.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Both B and C are correct
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.
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 B and C are correct
Why this is correct
Both B and C are valid syntax variations of the `ip route add` command that add the required route.
- ✗
ip route add 10.0.1.0/24 via 10.0.0.1 dev eth1
Why it's wrong here
This command is a valid syntax for adding the route; however, because another option also uses valid syntax, the correct answer is 'Both B and C are correct' (option A).
- ✗
ip route add 10.0.1.0/24 dev eth1 via 10.0.0.1
Why it's wrong here
This command is also a valid syntax for adding the route; similarly, it is correct but the best answer is option A.
- ✗
route add -net 10.0.1.0 netmask 255.255.255.0 gw 10.0.0.1 eth1
Why it's wrong here
This command uses the legacy `route` command with incorrect syntax. The interface name must be preceded by the `dev` keyword (e.g., `route add -net 10.0.1.0 netmask 255.255.255.0 gw 10.0.0.1 dev eth1`). Therefore, it is incorrect.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.