Google ACE Practice Question: Ensuring successful operation of a cloud solution
This ACE practice question tests your understanding of ensuring successful operation of a cloud solution. 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 company is running a batch processing job on Compute Engine every night. The job usually completes in 2 hours, but recently it has been taking over 4 hours. The CPU utilization on the VM is consistently below 20%. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The VM is running out of memory and swapping to disk.
The correct answer is C. When CPU utilization is below 20% but job execution time has doubled, the bottleneck is likely I/O, not compute. Swapping to disk occurs when the VM runs out of memory, causing the kernel to page memory to the persistent disk, which is orders of magnitude slower than RAM. This I/O wait directly increases job duration without raising CPU utilization.
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.
✗
The VM is using a shared-core machine type.
Why it's wrong here
Shared-core could cause CPU throttling but would also show varying CPU.
✗
The VM's machine type is too small.
Why it's wrong here
A too-small machine would show high CPU utilization.
✓
The VM is running out of memory and swapping to disk.
Why this is correct
Swapping causes high disk I/O and slow performance with low CPU.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The VM's persistent disk is in a different zone.
Why it's wrong here
Zone differences have minimal impact on performance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that low CPU utilization always means the machine is over-provisioned, but the trap here is that I/O-bound workloads (like memory swapping) can cause severe performance degradation while CPU remains idle, leading candidates to incorrectly choose a machine type or disk zone issue.
Trap categories for this question
Command / output trap
Shared-core could cause CPU throttling but would also show varying CPU.
Detailed technical explanation
How to think about this question
Under the hood, when memory pressure triggers swapping, the kernel's page-out daemon (kswapd) writes dirty pages to the swap space on the persistent disk. Even with SSD persistent disks, latency is ~1-10 ms per I/O operation versus ~100 ns for RAM, creating a massive performance penalty. In real-world scenarios, monitoring /proc/meminfo for SwapTotal and SwapFree, or using `vmstat` to check `si` (swap in) and `so` (swap out) columns, directly confirms swapping activity.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this ACE question in full detail.
Ensuring successful operation of a cloud solution — This question tests Ensuring successful operation of a cloud solution — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The VM is running out of memory and swapping to disk. — The correct answer is C. When CPU utilization is below 20% but job execution time has doubled, the bottleneck is likely I/O, not compute. Swapping to disk occurs when the VM runs out of memory, causing the kernel to page memory to the persistent disk, which is orders of magnitude slower than RAM. This I/O wait directly increases job duration without raising CPU utilization.
What should I do if I get this ACE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This ACE practice question is part of Courseiva's free Google Cloud 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 ACE exam.
Question Discussion
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