This LFCS practice question tests your understanding of service configuration. 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 custom service requires that the network is fully operational before it starts. Which directive should be added to the [Unit] section of the service's unit file to ensure this dependency?
After=network-online.target
Ensures service starts after network is fully up.
Requires=network.target
Why wrong: Ensures network.target is started, but not fully ready.
Wants=network-online.target
Why wrong: Weak dependency, does not enforce ordering.
After=network.target
Why wrong: Orders after network.target, but network may not be fully operational.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
After=network-online.target
Option A is correct because `After=network-online.target` ensures the service starts only after the network is fully operational, including IP address assignment and connectivity. This target is reached when network managers like systemd-networkd or NetworkManager confirm the network is online, making it suitable for services that require active network interfaces.
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.
After=network-online.target
Why this is correct
Ensures service starts after network is fully up.
Related concept
Read the scenario before looking for a memorised answer.
Requires=network.target
Why it's wrong here
Ensures network.target is started, but not fully ready.
Wants=network-online.target
Why it's wrong here
Weak dependency, does not enforce ordering.
After=network.target
Why it's wrong here
Orders after network.target, but network may not be fully operational.
Common exam traps
The trap here is that candidates confuse `network.target` (which is reached early and does not guarantee network readiness) with `network-online.target` (which waits for full network availability), leading them to pick option D or B incorrectly.
Detailed technical explanation
The `network-online.target` is a special systemd target that is pulled in by network management services (e.g., systemd-networkd-wait-online.service) and is reached only after all configured network interfaces are up and have obtained addresses (e.g., via DHCP). This contrasts with `network.target`, which is a passive synchronization point that does not wait for full connectivity. In real-world scenarios, services like NFS mounts or web servers that bind to specific IP addresses must use `After=network-online.target` to avoid startup failures due to missing routes or interfaces.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Service Configuration — This question tests Service Configuration — Read the scenario before looking for a memorised answer..
The correct answer is: After=network-online.target — Option A is correct because `After=network-online.target` ensures the service starts only after the network is fully operational, including IP address assignment and connectivity. This target is reached when network managers like systemd-networkd or NetworkManager confirm the network is online, making it suitable for services that require active network interfaces.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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