- A
Reduce the number of vCPUs for the database VMs from 16 to 8.
Why wrong: Reducing vCPUs would negatively impact database performance, as the workload benefits from parallel processing.
- B
Disable Hyper-Threading on the new cluster hosts.
Why wrong: Disabling HT would reduce CPU capacity, potentially worsening performance; HT is not the cause of the issue.
- C
Increase the memory reservation for each database VM to prevent ballooning.
Why wrong: Reserving memory prevents ballooning but does not fix NUMA-based performance degradation; it may also waste resources.
- D
Enable vNUMA for the database VMs to align with the physical NUMA topology.
vNUMA allows the guest OS to optimize memory access based on physical NUMA nodes, reducing remote memory access and improving performance.
Quick Answer
The answer is to enable vNUMA for the database VMs to align with the physical NUMA topology. This is the correct choice because the database VMs, with 16 vCPUs and 128 GB RAM, exceed the threshold that triggers vNUMA, but after migration to hosts with two NUMA nodes per socket, the guest OS may not be optimizing memory and CPU scheduling across the physical nodes. Without proper vNUMA alignment, the VM incurs costly remote memory accesses, causing high CPU ready time and ballooning despite ample host resources. On the VCP-DCV exam, this scenario tests your understanding of how vNUMA configuration for VM performance directly impacts large VMs across different hardware generations—a common trap is assuming resource contention is the issue when the real culprit is NUMA misalignment. Remember the memory tip: “If vCPUs exceed eight, check NUMA alignment to avoid a performance fate.”
VCP-DCV vSphere Performance and Scaling Practice Question
This VCP-DCV practice question tests your understanding of vsphere performance and scaling. 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 company operates a large vSphere environment with 32 ESXi hosts, each featuring 2 sockets, 12 cores per socket (2.6 GHz), and 256 GB RAM. The environment runs a mix of VMs, including several critical database VMs with 16 vCPUs and 128 GB RAM configured. After migrating these database VMs from an older cluster to a new cluster with identical hardware specifications, administrators observe significant performance degradation. vCenter performance charts show high memory ballooning and elevated CPU ready time for these VMs, while overall host utilization remains moderate (CPU 40%, RAM 60%). The new cluster's hosts have two NUMA nodes per socket (each NUMA node spans 6 cores and 64 GB RAM). The older cluster had hosts with a single NUMA node per socket. The administrator confirms that the VMs are running on hosts with sufficient free resources and that no other VMs are contending heavily. What is the most likely cause, and what should the administrator do to resolve the issue?
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 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
Enable vNUMA for the database VMs to align with the physical NUMA topology.
Option B is correct. The database VMs have 16 vCPUs and 128 GB RAM, which triggers vNUMA by default (more than 8 vCPUs). However, the VM's vNUMA topology may not align with the host's physical NUMA topology after migration. The new hosts have multiple NUMA nodes (two per socket), and the guest OS may not be optimized for that topology. Enabling vNUMA (or ensuring it is properly configured) aligns the VM's memory and CPU resources with the physical NUMA nodes, reducing remote memory access and improving performance. Option A is incorrect because increasing memory reservations prevents ballooning but does not address the underlying NUMA architecture issue; it may even limit flexibility. Option C is incorrect because reducing vCPUs might lower performance for the database workload. Option D is incorrect because enabling Hyper-Threading would increase logical CPUs but does not solve NUMA misalignment; it could even exacerbate the issue.
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.
- ✗
Reduce the number of vCPUs for the database VMs from 16 to 8.
Why it's wrong here
Reducing vCPUs would negatively impact database performance, as the workload benefits from parallel processing.
- ✗
Disable Hyper-Threading on the new cluster hosts.
Why it's wrong here
Disabling HT would reduce CPU capacity, potentially worsening performance; HT is not the cause of the issue.
- ✗
Increase the memory reservation for each database VM to prevent ballooning.
Why it's wrong here
Reserving memory prevents ballooning but does not fix NUMA-based performance degradation; it may also waste resources.
- ✓
Enable vNUMA for the database VMs to align with the physical NUMA topology.
Why this is correct
vNUMA allows the guest OS to optimize memory access based on physical NUMA nodes, reducing remote memory access and improving performance.
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.
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.
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vSphere Performance and Scaling — study guide chapter
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FAQ
Questions learners often ask
What does this VCP-DCV question test?
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: Enable vNUMA for the database VMs to align with the physical NUMA topology. — Option B is correct. The database VMs have 16 vCPUs and 128 GB RAM, which triggers vNUMA by default (more than 8 vCPUs). However, the VM's vNUMA topology may not align with the host's physical NUMA topology after migration. The new hosts have multiple NUMA nodes (two per socket), and the guest OS may not be optimized for that topology. Enabling vNUMA (or ensuring it is properly configured) aligns the VM's memory and CPU resources with the physical NUMA nodes, reducing remote memory access and improving performance. Option A is incorrect because increasing memory reservations prevents ballooning but does not address the underlying NUMA architecture issue; it may even limit flexibility. Option C is incorrect because reducing vCPUs might lower performance for the database workload. Option D is incorrect because enabling Hyper-Threading would increase logical CPUs but does not solve NUMA misalignment; it could even exacerbate the issue.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on VCP-DCV
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company's vSphere environment experiences intermittent performance degradation on a critical virtual machine. The VM has 8 vCPUs allocated, and the host has 16 physical cores (2 sockets, 8 cores each). The VM is configured with Hyper-Threading enabled. Which action is most likely to improve performance without increasing resource allocation?
easy- ✓ A.Change the VM's CPU affinity to pin it to one socket
- B.Enable CPU hot-add for the VM
- C.Increase the VM's memory reservation
- D.Disable Hyper-Threading on the host
Why A: Option B is correct because pinning the VM to one socket can reduce NUMA cross-socket latency, improving performance for the 8-vCPU VM. Option A is wrong because disabling Hyper-Threading generally reduces throughput. Option C is wrong as memory reservation does not directly affect CPU performance. Option D is wrong as CPU hot-add does not improve performance; it allows adding CPUs later.
Last reviewed: Jun 24, 2026
This VCP-DCV practice question is part of Courseiva's free VMware 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 VCP-DCV exam.
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