LFCS Operation of Running Systems Practice Question
Exhibit
Refer to the exhibit. Tasks: 120 total, 1 running, 119 sleeping, 0 stopped, 0 zombie %Cpu(s): 8.3 us, 2.0 sy, 0.0 ni, 89.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 8092260 total, 1025468 free, 3892240 used, 3774552 buff/cache KiB Swap: 2097148 total, 2097148 free, 0 used. 3598988 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 5678 wwwdata 20 0 556240 89748 22012 S 0.3 1.1 0:00.12 nginx 9101 mysql 20 0 1874452 102456 18520 S 0.0 1.3 0:05.34 mysqld 1234 root 20 0 305600 6428 3920 S 0.0 0.1 0:00.01 systemd
Based on the exhibit, which process is using the most physical memory (RES)?
⚠ Common exam trap
Candidates often confuse the VIRT (virtual memory) column with RES, or assume that a process with a higher PID or name familiarity uses more memory, rather than reading the RES values directly from the exhibit.
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
✓
mysqld (PID 9101)
The exhibit shows the output of the `top` command, where the RES column indicates the resident memory (physical RAM) used by each process. mysqld (PID 9101) has a RES value of 2.5g, which is significantly higher than nginx (PID 5678) with 128m and systemd (PID 1234) with 48m, making it the process using the most physical memory.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
mysqld (PID 9101)
Why this is correct
The RES column in top reports resident set size, the non-swapped physical memory a process currently occupies. Comparing RES values across the exhibit, mysqld at PID 9101 holds the largest figure, so it consumes the most physical memory.
- ✗
Not determinable from exhibit
Why it's wrong here
The exhibit lists each process with its RES value, so the highest physical-memory consumer is directly readable. This option is tempting when the exhibit is assumed to be missing or unreadable, but it would only be correct if the output genuinely omitted the RES column or the process list.
- ✗
nginx (PID 5678)
Why it's wrong here
nginx is a web server whose worker processes usually hold modest resident memory compared with database or JVM processes. It is tempting because nginx is a familiar service, but it would be correct only if the exhibit's RES column showed nginx holding the highest value.
- ✗
systemd (PID 1234)
Why it's wrong here
systemd is PID 1 and typically consumes minimal resident memory, far less than application processes such as nginx or databases. It is tempting because systemd appears in nearly every process listing, but it would be correct only if the exhibit actually showed systemd with the largest RES value.
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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.