The answer is a VM memory limit set too low. This is correct because a memory limit acts as a hard cap on the amount of physical host memory a virtual machine can consume, regardless of how much free memory exists on the host. When the VM’s active memory usage reaches that artificially low ceiling, the vSphere memory balloon driver inflates inside the guest OS to reclaim pages and enforce the limit, causing sporadic ballooning even when the host has ample physical RAM. On the VMware Certified Professional Data Center Virtualization VCP-DCV exam, this scenario tests your understanding of memory reclamation mechanisms and the distinction between limits, reservations, and shares—a common trap is confusing ballooning with host memory pressure or swap issues. Remember the mnemonic: “Limit low, balloon blow”—if you see unexpected ballooning on a host with free memory, always check the VM’s memory limit first.
VCP-DCV vSphere Performance and Scaling Practice Question
This VCP-DCV practice question tests your understanding of vsphere performance and scaling. 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 vSphere administrator notices high memory ballooning on a host running multiple VMs with large memory allocations. The host has sufficient physical memory, but ballooning occurs sporadically. 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's memory limit is set too low
Option D is correct because a low memory limit forces the VM to balloon even if the host has free memory. Option A is wrong as CPU overcommitment does not cause memory ballooning. Option B is wrong because reservation higher than physical would prevent VM power-on. Option C is wrong as insufficient swap space would not cause ballooning; ballooning is a driver-based memory reclamation.
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 host is overcommitted on CPU
Why it's wrong here
CPU overcommitment causes CPU ready time, not memory ballooning.
✓
The VM's memory limit is set too low
Why this is correct
A memory limit below the VM's active memory forces the balloon driver to reclaim memory from the guest, even if host has free memory.
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 memory is set to a reservation higher than the physical memory
Why it's wrong here
A reservation higher than available physical memory prevents the VM from powering on.
✗
The host has insufficient swap space
Why it's wrong here
Insufficient swap space can cause swapping failures, but ballooning is a proactive reclamation method independent of swap space.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 VCP-DCV 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 VCP-DCV exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
vSphere Performance and Scaling — This question tests vSphere Performance and Scaling — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The VM's memory limit is set too low — Option D is correct because a low memory limit forces the VM to balloon even if the host has free memory. Option A is wrong as CPU overcommitment does not cause memory ballooning. Option B is wrong because reservation higher than physical would prevent VM power-on. Option C is wrong as insufficient swap space would not cause ballooning; ballooning is a driver-based memory reclamation.
What should I do if I get this VCP-DCV question wrong?
Identify which VCP-DCV exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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Question Discussion
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