VCP-DCV vSphere Performance and Scaling Practice Question
A vSphere cluster is experiencing high CPU ready time across multiple hosts during peak hours. The cluster consists of 8 hosts, each with 2 sockets and 8 cores per socket (hyperthreading enabled). DRS is set to a moderately aggressive migration threshold. The administrator needs to reduce CPU contention without disrupting workloads. Which three actions should the administrator consider? (Choose three.)
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
✓
Upgrade the ESXi hosts to models with higher CPU clock speeds.
Enabling hyperthreading increases logical CPUs and can reduce ready time. Reducing the number of VMs per host decreases overall demand. Upgrading to faster CPUs increases per-core capacity. Setting CPU affinity on VMs is not recommended as it limits DRS balancing. Increasing the DRS migration threshold to the most aggressive may cause excessive migrations and does not address the root cause. Adding vCPUs to VMs would worsen contention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Upgrade the ESXi hosts to models with higher CPU clock speeds.
Why this is correct
Faster CPUs improve per-core performance, reducing the impact of contention.
- ✓
Reduce the number of VMs running on each host.
Why this is correct
Fewer VMs per host reduces overall CPU demand and contention.
- ✓
Ensure Hyper-Threading is enabled on all hosts.
Why this is correct
Enabling Hyper-Threading doubles the number of logical CPUs, which can help reduce CPU ready time.
- ✗
Configure CPU affinity for VMs with high vCPU counts.
Why it's wrong here
CPU affinity is not a best practice and can prevent DRS from balancing effectively.
- ✗
Increase the DRS migration threshold to the most aggressive setting.
Why it's wrong here
An overly aggressive threshold can cause unnecessary migrations and instability.
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Variation 1. Refer to the exhibit. An administrator runs esxtop and sees the above output for a virtual machine. What is the most likely cause of the performance issue?
medium- A.The VM is running on a host with Hyper-Threading disabled.
- B.The memory of the VM is overcommitted.
- C.The host has too many other VMs competing for resources.
- ✓ D.The VM has too many vCPUs for the available physical cores.
- E.The VM has CPU affinity configured to a single core.
Why D: The exhibit shows a virtual machine with 8 vCPUs but only 4 physical cores (PCPU) available, as indicated by the %USED and %RUN columns. This leads to CPU ready time (%RDY) being high, which is a classic symptom of CPU overcommitment where the VM's vCPU count exceeds the available physical cores, causing scheduling contention. Option D is correct because the VM has too many vCPUs for the available physical cores, resulting in excessive ready time and degraded performance.
Variation 2. Which TWO actions are effective in reducing CPU ready time on a vSphere host that is heavily overcommitted on CPU? (Choose two.)
easy- ✓ A.Add more hosts to the cluster.
- B.Enable hyperthreading on the host CPUs.
- C.Increase the number of vCPUs on VMs with high ready times.
- ✓ D.Reduce the number of vCPUs on over-provisioned VMs.
- E.Configure CPU affinity to pin vCPUs to specific pCPUs.
Why A: Reducing the number of vCPUs on over-provisioned VMs directly decreases scheduling contention. Adding more hosts to the cluster increases the pool of physical CPUs, reducing overcommitment. Increasing vCPUs worsens the issue. Enabling hyperthreading does not reduce ready time if the host is already CPU-bound. Configuring CPU affinity restricts scheduling and can increase ready time.
Variation 3. Which TWO actions can be taken to reduce CPU ready time for a virtual machine? (Select TWO.)
medium- A.Enable CPU hot-add and hot-plug for the VM
- ✓ B.Decrease the number of vCPUs to match the workload
- C.Migrate the VM to a host with more physical CPU cores
- ✓ D.Increase the CPU shares for the VM
- E.Add more vCPUs to the VM
Why B: Reducing the number of vCPUs to match the actual workload demand directly decreases the co-scheduling overhead and contention for physical CPU cores. When a VM has more vCPUs than its workload requires, the ESXi scheduler must wait for all assigned vCPUs to become available simultaneously, which inflates CPU ready time. Right-sizing vCPUs to the workload is a best practice to minimize ready time and improve performance.
Variation 4. Which three actions can reduce CPU ready time for a virtual machine in a vSphere cluster? (Choose three.)
medium- A.Enable CPU hot-add on the VM
- B.Set the VM's CPU affinity manually
- ✓ C.Place the VM on a host with lower CPU utilization
- ✓ D.Reduce the number of vCPUs allocated to the VM
- ✓ E.Increase the host's physical CPU count by adding a new host to the cluster
Why C: The correct options are C, D, and E. Placing the VM on a host with lower CPU utilization (C) reduces contention for CPU resources, thereby lowering CPU ready time. Reducing the number of vCPUs allocated to the VM (D) decreases the CPU demand, reducing the time the VM spends waiting for physical CPU cycles. Increasing the host's physical CPU count by adding a new host to the cluster (E) provides more CPU resources overall, which can reduce ready time. Option A, enabling CPU hot-add, does not reduce existing CPU ready time; it only allows adding vCPUs later without rebooting, which could increase contention. Option B, setting CPU affinity manually, often reduces the scheduler's flexibility and can increase ready time, not decrease it.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.