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 system administrator manages a database server service (database.service) that experiences periodic CPU spikes, causing excessive load on the server. The administrator wants to limit the service's CPU usage to 25% of a single CPU core. The service is running on a system with cgroup v2. Which directive should be added to the [Service] section of the unit file to achieve this?
CPUAccounting=true
Why wrong: Enables account but does not limit.
CPUQuota=25%
Sets a hard limit on CPU usage.
CPUWeight=100
Why wrong: Sets weight, not a hard limit.
CPUShares=256
Why wrong: For cgroup v1, sets relative weight.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
CPUQuota=25%
Option B is correct because in cgroup v2, the `CPUQuota=` directive in a systemd unit file directly limits the CPU time a service can use, expressed as a percentage of a single CPU core. Setting `CPUQuota=25%` restricts the service to using at most 25% of one core, which matches the administrator's requirement to cap CPU usage at 25% of a single core.
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.
CPUAccounting=true
Why it's wrong here
Enables account but does not limit.
CPUQuota=25%
Why this is correct
Sets a hard limit on CPU usage.
Related concept
Read the scenario before looking for a memorised answer.
CPUWeight=100
Why it's wrong here
Sets weight, not a hard limit.
CPUShares=256
Why it's wrong here
For cgroup v1, sets relative weight.
Common exam traps
The trap here is that candidates often confuse `CPUQuota=` (a hard limit) with `CPUWeight=` or `CPUShares=` (relative priority settings), mistakenly thinking a weight or share value can enforce a specific percentage cap on CPU usage.
Detailed technical explanation
Under cgroup v2, `CPUQuota=` works by configuring the `cpu.max` controller, which specifies a quota (maximum CPU time in microseconds) over a period (default 100ms). For example, `CPUQuota=25%` translates to a quota of 25,000 µs per 100,000 µs period, ensuring the service cannot exceed 25% of a single core. This is a hard limit, unlike `CPUWeight=`, which only affects scheduling priority when CPU is contended, and does not prevent a service from using 100% CPU if no other processes are competing.
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: CPUQuota=25% — Option B is correct because in cgroup v2, the `CPUQuota=` directive in a systemd unit file directly limits the CPU time a service can use, expressed as a percentage of a single CPU core. Setting `CPUQuota=25%` restricts the service to using at most 25% of one core, which matches the administrator's requirement to cap CPU usage at 25% of a single core.
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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