The answer is that the host has too many vCPUs relative to physical cores, so reducing the vCPU count on some VMs is the correct solution. This is because the host contains only 32 physical cores (2 CPUs × 16 cores), yet the six VMs each with 8 vCPUs total 48 vCPUs, creating a vCPU-to-core ratio of 1.5:1. When CPU ready time averages exceed 20%, it signals severe contention where the hypervisor cannot schedule all vCPUs simultaneously, forcing many to wait in the ready queue. On the VMware Certified Professional Data Center Virtualization VCP-DCV exam, this scenario tests your understanding of CPU scheduling fundamentals and the impact of over-provisioning—a common trap is to blame storage latency or memory ballooning instead. A useful memory tip: think of physical cores as highway lanes; if you have 48 cars (vCPUs) trying to use only 32 lanes, traffic jams (high ready time) are inevitable.
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.
An administrator notices that a critical VM running a database has a high CPU ready time average (over 20%) on a host with 2 physical CPUs (16 cores each). The host is running 6 VMs, each with 8 vCPUs. What is the most likely cause of the high ready time?
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 host has too many vCPUs relative to physical cores; reduce vCPU count on some VMs.
Option B is correct because the host has 32 physical cores (2 CPUs × 16 cores) but the 6 VMs each with 8 vCPUs total 48 vCPUs, resulting in a vCPU-to-core ratio of 1.5:1. A CPU ready time average over 20% indicates severe contention for physical cores, as the hypervisor cannot schedule all vCPUs simultaneously. Reducing the vCPU count on some VMs would lower the ratio and alleviate the scheduling bottleneck.
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.
✗
Hyper-Threading should be disabled to reduce scheduling overhead.
Why it's wrong here
Incorrect: Disabling HT reduces available logical CPUs, worsening the overcommitment.
✓
The host has too many vCPUs relative to physical cores; reduce vCPU count on some VMs.
Why this is correct
Correct: vCPU overcommitment leads to high ready time.
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 VMs are not configured with NUMA awareness.
Why it's wrong here
Incorrect: NUMA awareness helps memory locality but does not directly reduce CPU ready time.
✗
Memory overcommitment is causing excessive swapping.
Why it's wrong here
Incorrect: The issue is CPU-related, not memory.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse CPU ready time with memory pressure (Option D) or assume Hyper-Threading is the culprit (Option A), when the core issue is simply an over-provisioned vCPU-to-core ratio.
Detailed technical explanation
How to think about this question
CPU ready time is the percentage of time a vCPU is ready to run but waiting for a physical core to become available, measured by the ESXi scheduler. With a vCPU-to-core ratio exceeding 1.0, the hypervisor uses a co-scheduling algorithm (relaxed co-scheduling in modern vSphere) to allocate time slices, but oversubscription beyond 1.5:1 often leads to significant contention. In real-world scenarios, database VMs are particularly sensitive to ready time because they rely on consistent CPU availability for transaction processing.
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
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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 host has too many vCPUs relative to physical cores; reduce vCPU count on some VMs. — Option B is correct because the host has 32 physical cores (2 CPUs × 16 cores) but the 6 VMs each with 8 vCPUs total 48 vCPUs, resulting in a vCPU-to-core ratio of 1.5:1. A CPU ready time average over 20% indicates severe contention for physical cores, as the hypervisor cannot schedule all vCPUs simultaneously. Reducing the vCPU count on some VMs would lower the ratio and alleviate the scheduling bottleneck.
What should I do if I get this VCP-DCV 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.
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. An administrator notices that a critical virtual machine is running slowly. The VM has 8 vCPUs and 32GB memory. The host is an ESXi 7.0 server with two Intel Xeon Gold 6248 sockets (20 cores each, hyperthreading enabled). The VM's CPU ready time is consistently above 10%. What is the most likely cause?
medium
A.The VM's vCPUs are pinned to a single NUMA node causing contention.
✓ B.The host has too many VMs running and CPU oversubscription is too high.
C.The VM is over-provisioned on vCPUs relative to the host's physical cores.
D.The VM is using Eager Zero Thick disks causing high I/O latency.
Why B: High CPU ready time indicates the VM is ready to run but the hypervisor cannot schedule it. This is typically due to excessive CPU oversubscription. Option A is incorrect because 8 vCPUs is not over-provisioned relative to 80 logical CPUs. Option B is incorrect as NUMA pinning generally affects memory locality, not ready time. Option D is incorrect because disk I/O does not cause CPU ready time.
Variation 2. During a performance review, an administrator notices that a VM with 4 vCPUs and 16 GB memory is experiencing over 10% CPU ready time. The host has two 8-core sockets (hyper-threading enabled) and 256 GB memory. The host runs 15 other VMs with varying CPU loads. What is the most likely cause?
✓ D.Over-provisioning of vCPUs on the host leading to contention.
Why D: Option D is correct because the host has 16 physical cores (with hyper-threading, 32 logical processors), but running 16 VMs with a total of 4 vCPUs each would require 64 vCPUs. This 2:1 over-provisioning ratio, combined with varying CPU loads, leads to contention for physical CPU resources, manifesting as CPU ready time exceeding 10%. CPU ready time measures the percentage of time a VM is ready to run but waiting for a physical CPU to become available.
Variation 3. An administrator is troubleshooting a VM that is running slowly. The VM has 4 vCPUs and 16 GB of memory. The host has 2 physical CPUs with 10 cores each, hyper-threading enabled. The administrator runs esxtop and sees that %RDY for the VM is consistently above 15%. Which action would most likely reduce the ready time?
medium
A.Increase the CPU shares for the VM.
B.Increase the number of vCPUs to 8 to improve parallelism.
C.Increase the memory allocation to 32 GB.
✓ D.Reduce the number of vCPUs to 2 if the workload does not require 4.
Why D: A %RDY value consistently above 15% indicates the VM is ready to run but is waiting for CPU scheduling time on the host. With 4 vCPUs on a host that has 20 logical CPUs (2 sockets × 10 cores × 2 threads), the VM is likely over-provisioned relative to its workload needs, causing co-scheduling contention. Reducing the number of vCPUs to 2 decreases the co-scheduling demands and reduces ready time, as the VM will require fewer physical CPUs to be available simultaneously.
Variation 4. An administrator is troubleshooting a virtual machine that experiences intermittent performance issues. The VM is configured with 8 vCPUs and 32 GB memory. The administrator runs esxtop and sees that the %RDY for the VM is consistently above 20%. What does this indicate?
hard
✓ A.The VM is contending for CPU resources due to overallocation of vCPUs.
B.The VM's virtual disks are experiencing high latency.
C.The VM is experiencing memory ballooning.
D.The VM is using its CPU resources efficiently.
Why A: Option D is correct because high %RDY means the VM is ready to run but is waiting for CPU resources from the hypervisor; this indicates CPU overcommitment. Option A is incorrect because high %RDY does not directly correlate with memory. Option C is incorrect because storage latency is not shown in CPU %RDY. Option B is incorrect because high %RDY is a sign of CPU contention, not just normal utilization.
Variation 5. Refer to the exhibit. The vSphere administrator observes that vm1 has a %RDY value of 20.5. What is the most likely cause of this high ready time?
hard
A.The VM is experiencing network packet loss
B.The VM's virtual disk is causing I/O latency
✓ C.The host's physical CPUs are overcommitted
D.Insufficient memory is allocated to vm1
Why C: High %RDY indicates the VM is ready to run but is being queued due to CPU contention. This is typically caused by overcommitment of pCPUs. Memory or storage latency would show in other counters.
Last reviewed: Jun 11, 2026
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