The answer is that the vNUMA nodes are not aligned with the physical NUMA topology. When a large VM with 32 vCPUs is deployed on a host with two physical NUMA nodes, each containing 8 cores (16 threads with Hyper-Threading), vSphere automatically creates multiple virtual NUMA (vNUMA) nodes to reflect the guest’s size. However, if the VM’s vCPU count and memory allocation do not map precisely to the underlying physical node boundaries—for instance, if the VM spans both physical nodes without proper vNUMA alignment—the guest OS will frequently access memory from a remote NUMA node, causing severe performance degradation. On the VCP-DCV exam, this scenario tests your understanding of vNUMA best practices for large VMs, where a common trap is assuming that adding more memory or disabling Hyper-Threading fixes alignment issues. Remember the key tip: for optimal NUMA alignment, ensure the VM’s vCPU count is a multiple of the physical node’s core count, and its memory fits within a single node’s capacity.
VCP-DCV vSphere Performance and Scaling Practice Question
This VCP-DCV practice question tests your understanding of vsphere performance and scaling. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 database VM with 32 vCPUs and 256 GB memory is deployed on a host with two NUMA nodes, each with 8 cores (16 threads with HT). The application performs badly. Analysis shows high remote memory access. What is the MOST LIKELY reason?
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 vNUMA nodes are not aligned with the physical NUMA nodes.
With 32 vCPUs, the VM exceeds the default vNUMA node size of 8 cores, so vSphere will expose multiple vNUMA nodes. However, if vNUMA is not correctly configured or if the VM's memory size forces it to span physical NUMA nodes, the guest OS may not optimize memory locality. The most common cause is that the VM's vCPUs and memory are not aligned with the physical NUMA topology, leading to remote memory access. Disabling hyperthreading would not help alignment, nor would adding more memory.
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.
✗
Hyperthreading is enabled causing CPU contention.
Why it's wrong here
Hyperthreading may increase contention but does not directly cause remote memory access.
✓
The vNUMA nodes are not aligned with the physical NUMA nodes.
Why this is correct
Misalignment causes the guest to access memory from remote NUMA nodes, increasing latency.
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 host's NUMA nodes are not balanced in memory capacity.
Why it's wrong here
While unbalanced memory capacity could contribute, the primary issue is vCPU/vMEM alignment with NUMA topology.
✗
The VM has too much memory allocated.
Why it's wrong here
More memory does not inherently cause remote access; alignment is key.
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 vNUMA nodes are not aligned with the physical NUMA nodes. — With 32 vCPUs, the VM exceeds the default vNUMA node size of 8 cores, so vSphere will expose multiple vNUMA nodes. However, if vNUMA is not correctly configured or if the VM's memory size forces it to span physical NUMA nodes, the guest OS may not optimize memory locality. The most common cause is that the VM's vCPUs and memory are not aligned with the physical NUMA topology, leading to remote memory access. Disabling hyperthreading would not help alignment, nor would adding more memory.
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 →
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 large VM with 24 vCPUs is deployed on a dual-socket host with two NUMA nodes each having 12 cores. Which step is a BEST PRACTICE to ensure optimal performance for this VM?
medium
A.Disable hyperthreading on the host to reduce contention.
B.Assign all vCPUs to a single NUMA node using CPU affinity.
✓ C.Leave vNUMA enabled and ensure the VM has enough memory to span two nodes.
D.Set the VM memory reservation to zero to allow transparent page sharing.
Why C: Setting vNUMA controls exposes the NUMA topology to the guest OS, allowing it to optimize memory locality. By default, vNUMA is enabled for VMs with more than 8 vCPUs. Placing the VM on a single NUMA node would limit resources. Disabling hyperthreading is unnecessary. Setting CPU affinity reduces flexibility.
Variation 2. Which two factors most directly influence vSphere NUMA scheduling decisions for a VM? (Choose two.)
easy
✓ A.Host NUMA node topology
B.VM memory reservation
✓ C.Number of vCPUs
D.VM storage policy
E.Virtual machine version
Why A: The correct options are A and C. vSphere NUMA scheduling uses the number of vCPUs and the host NUMA node topology to place the VM on a single node. Memory reservation and VM version are secondary. Storage policy is not relevant.
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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.
Question Discussion
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