This EX200 practice question tests your understanding of operate running systems. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 is troubleshooting a custom service called 'database.service' that fails intermittently. The service is a proprietary database that requires large amounts of memory. The administrator runs systemctl status database and sees 'Active: failed (Result: core-dump)' and the journal shows 'Out of memory: Killed process (database) total-vm:...' The server has 8GB RAM and 2 CPU cores. The service unit file does not contain any memory limits. The application is configured to use up to 4GB. The administrator suspects the systemd service is being killed by the OOM killer. Which action should the administrator take to prevent this issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set OOMScoreAdjust=-1000 in the service unit file.
Option B is correct because setting OOMScoreAdjust=-1000 makes the systemd service less likely to be targeted by the OOM killer. The OOM killer selects processes based on a badness score; a lower score (down to -1000) reduces the likelihood of being killed. Since the service is already configured to use up to 4GB and the server has 8GB RAM, adjusting the OOM score is the targeted fix without disabling kernel protections or over-allocating resources.
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.
✗
Set MemoryMax=6G in the service unit file.
Why it's wrong here
Incorrect: This limits the cgroup memory but does not prevent OOM kills; if the system runs out of memory, the process may still be killed.
✓
Set OOMScoreAdjust=-1000 in the service unit file.
Why this is correct
Correct: This makes the process less likely to be selected by the OOM killer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Modify kernel parameters to disable the OOM killer.
Why it's wrong here
Incorrect: Disabling OOM killer system-wide is not recommended and may cause system hangs.
✗
Increase swap space to 16GB.
Why it's wrong here
Incorrect: Increasing swap only delays OOM conditions; the process can still be killed if memory pressure persists.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse systemd's cgroup memory limits (MemoryMax) with the kernel OOM killer's scoring mechanism, or they think disabling the OOM killer or adding swap is a safe solution, when the correct approach is to adjust the OOM score to protect the specific service.
Detailed technical explanation
How to think about this question
The OOM killer calculates a 'badness' score for each process based on factors like memory usage, runtime, and oom_score_adj. By default, oom_score_adj is 0; setting it to -1000 (the minimum) reduces the process's contribution to the badness score by 1000 points, making it the least likely to be killed. This is different from MemoryMax, which enforces a hard cgroup limit and can cause immediate SIGKILL from systemd if exceeded, whereas OOMScoreAdjust works with the kernel's OOM killer heuristic. In practice, for memory-intensive services that must not be killed, this adjustment is often combined with appropriate memory limits and monitoring.
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 practitioner preparing for the EX200 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
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.
Operate running systems — This question tests Operate running systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set OOMScoreAdjust=-1000 in the service unit file. — Option B is correct because setting OOMScoreAdjust=-1000 makes the systemd service less likely to be targeted by the OOM killer. The OOM killer selects processes based on a badness score; a lower score (down to -1000) reduces the likelihood of being killed. Since the service is already configured to use up to 4GB and the server has 8GB RAM, adjusting the OOM score is the targeted fix without disabling kernel protections or over-allocating resources.
What should I do if I get this EX200 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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