VCP-DCV vSphere Performance and Scaling Practice Test 7 — 15 Questions

Question 1

A vSphere administrator is troubleshooting a VM that shows high 'CPU ready' time in vCenter performance charts. The host has 32 logical CPUs (16 cores with HT). Which tool should be used to identify which other VMs are contending for CPU resources?

Accepted Answer

Esxtop with CPU world view. Option D is correct because esxtop with the CPU world view shows per-vCPU ready time and which worlds are consuming CPU. Option A is wrong; vCenter charts show aggregate VM ready time but not per-world contention. Option B is wrong; resxtop is remote esxtop, but 'CPU view' refers to the summary view; the CPU world view is more detailed. Option C is wrong; vROps can show trends but not real-time per-world details.

Answer

vRealize Operations Manager

Answer

Resxtop with CPU view

Answer

vCenter Resource Allocation chart

Question 2

An administrator configures a resource pool with a reservation of 10 GHz and a limit of 20 GHz. The pool contains two VMs: VM1 has a reservation of 6 GHz and no limit, VM2 has no reservation and a limit of 8 GHz. The host has only 12 GHz available. During peak usage, both VMs demand more than their shares. Which statement is true?

Accepted Answer

VM1 gets at least 6 GHz, VM2 gets at most 8 GHz, but because the pool limit is 20 GHz and host only 12, VM2's limit is effectively 6 GHz after VM1's reservation. Option B is correct. The resource pool has a limit of 20 GHz, but host only has 12 GHz. VM1 has 6 GHz reservation, so it gets at least that. VM2 has a limit of 8 GHz, but after VM1's reservation only 6 GHz remains on the host, which is within VM2's 8 GHz limit, so VM2 gets 6 GHz. The pool's reservation is satisfied (6+6=12 >=10). Option A is wrong because it ignores that host capacity is less than pool limit. Option C is wrong because VM2 cannot get 8 GHz due to host limit. Option D is wrong because pool reservation does not allocate additional resources.

Answer

VM1 gets at least 6 GHz, VM2 gets at most 8 GHz, and the remaining 4 GHz is divided by share

Answer

VM1 gets exactly 6 GHz, VM2 gets exactly 8 GHz, and the pool's reservation is ignored

Answer

VM1 gets at least 6 GHz, VM2 gets at least 2 GHz due to pool reservation, and both use remaining as share

Question 3

A vSphere cluster uses vSAN with deduplication and compression enabled. An administrator notices that IOPS for a VM is lower than expected despite low CPU and memory utilization on hosts. Which of the following is most likely the cause?

Accepted Answer

Deduplication and compression overhead is causing increased CPU usage on storage controller. Option C is correct because deduplication and compression use CPU on each host, which can become a bottleneck for IOPS. Option A is wrong; repair is done at off-peak. Option B is wrong; read cache reservation is not a primary cause. Option D is wrong; capacity utilization itself does not directly reduce IOPS unless near full causing rebalance.

Answer

The VM storage policy has no read cache reservation

Answer

vSAN object repair is consuming disk bandwidth

Answer

The VM is running on a host with a vSAN disk capacity tier that is 80% full

Question 4

An administrator configures a VM with 4 vCPUs and 32 GB memory on a host with 128 GB RAM and 8 cores (HT enabled). The VM runs a database that requires high memory bandwidth. Performance monitoring shows low CPU usage but high memory latency. Which configuration change is most likely to improve memory performance?

Accepted Answer

Enable the 'Preferred NUMA Node' VM option. Option A is correct because Preferred NUMA Node allows the VM to be pinned to a specific NUMA node, reducing cross-node memory access. Option B is wrong; increasing reservation does not improve latency. Option C is wrong; disabling HT reduces overall throughput. Option D is wrong; more vCPUs may increase contention.

Answer

Increase the memory reservation to 64 GB

Answer

Disable Hyper-Threading on the host

Answer

Increase the number of vCPUs to 8

Question 5

Which two factors most directly influence vSphere NUMA scheduling decisions for a VM? (Choose two.)

Accepted Answer

Host NUMA node topology. 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.

Answer

VM memory reservation

Answer

VM storage policy

Answer

Virtual machine version

Question 6

Which three actions can reduce CPU ready time for a virtual machine in a vSphere cluster? (Choose three.)

Accepted Answer

Place the VM on a host with lower CPU utilization. The correct options are B, D, and E. Reducing vCPUs reduces contention, adding hosts increases resources, and placing on less loaded host reduces ready time. Hot-add does not reduce ready time; manual CPU affinity can worsen.

Answer

Enable CPU hot-add on the VM

Answer

Set the VM's CPU affinity manually

Question 7

An administrator is troubleshooting a VM that is running slowly. Esxtop shows the VM has high %SWPWV (swap wait). Which three conditions could cause this? (Choose three.)

Accepted Answer

The host is overcommitted on memory. The correct options are A, C, and E. Swap wait occurs when the VM is waiting for swapped memory. A limit lower than active forces swapping. Host memory overcommitment causes swapping. Slow vswap storage increases latency. CPU overcommitment does not cause swap wait. Reservation equal to configured size would prevent swapping.

Answer

The VM has a memory reservation equal to its configured size

Answer

The host is overcommitted on CPU

Question 8

A small financial services company runs a critical trading application on a single vSphere host with two NUMA nodes (each with 8 cores). The VM is configured with 12 vCPUs and 64 GB memory. The application is not yet live, but load testing shows that CPU performance is satisfactory, but memory bandwidth is lower than expected. The application is known to benefit from fast memory access within a single NUMA domain. The administrator notices that the VM's memory is spread across both NUMA nodes. The administrator wants to force the VM to use only one NUMA node to maximize performance. However, the VM requires 12 vCPUs, which exceeds the 8 physical cores per node. What is the best course of action to improve memory bandwidth for this VM?

Accepted Answer

Keep the vCPU count at 12 but configure a NUMA Affinity to prefer the first NUMA node, and accept some cross-node memory access.. Option C is correct: Using NUMA affinity to prefer one node keeps most memory local, but vCPU count exceeds core count, so some vCPUs will still run on the second node. However, memory can be allocated from the preferred node as much as possible, reducing cross-node latency. Option A is wrong because reducing vCPUs may affect application performance. Option B is wrong because CPU affinity to only one node would starve vCPUs as there are only 8 cores, causing high ready time. Option D is wrong; Hyper-Threading does not change physical core count; 12 vCPUs still exceed 8 cores per node, and HT does not enable single-node placement.

Answer

Enable Hyper-Threading and reassign vCPUs to 12, and the VM will automatically run within one NUMA node.

Answer

Keep the vCPU count at 12 but set CPU affinity to the first NUMA node only, leaving the second node unused.

Answer

Reduce the number of vCPUs to 8 to fit within one NUMA node, and keep the same memory size.

Question 9

A large e-commerce company has a vSphere cluster with 16 hosts, each with 2 sockets of 10 cores (HT enabled) and 512 GB RAM. They run a mix of web and database VMs. During the holiday season, some VMs experience high CPU ready time, especially the database VMs. DRS is set to Fully Automated and migration thresholds are at default. The administrator notices that the cluster's CPU utilization averages at 60%, but some hosts are at 90% while others are at 30%. The VMs with high ready time are all on the highly utilized hosts. To resolve this, the administrator considers several options. Which action will most effectively balance CPU load and reduce ready time for the database VMs?

Accepted Answer

Decrease the DRS migration threshold from 3 to 1 to make it more aggressive.. Option A is correct. Decreasing the DRS migration threshold from 3 to 1 makes DRS more aggressive, migrating VMs even for small imbalances, thus spreading load more evenly. Option B is wrong; VM Monitoring is for fault detection, not load balancing. Option C is wrong; increasing the threshold makes DRS less aggressive, worsening the imbalance. Option D is wrong; shares only affect contention within a host, not migration triggers.

Answer

Create a resource pool for database VMs and set a higher CPU share value.

Answer

Increase the DRS migration threshold from 3 to 5 to reduce unnecessary migrations.

Answer

Enable 'VM Monitoring' in the HA cluster settings.

Question 10

A managed hosting provider uses vSphere 7 with vSAN to run customer VMs. One customer's VM is a SQL Server database with 8 vCPUs and 128 GB RAM. The administrator notices that the VM's performance during peak hours is poor, with high disk latency and occasional disconnects. The cluster has 4 hosts, each with 10 cores (HT enabled) and 256 GB RAM. vSAN is configured with a hybrid disk group (SSD cache, HDD capacity) per host. The VM's storage policy is set to 'Performance' with RAID-1 mirroring (2 copies). The administrator runs esxtop and sees high %DAVG (device average latency) for the VM's vmdk. The observed latency averages 30 ms, but spikes to 100 ms. The host where the VM is running has relatively low CPU and memory usage, and the vSAN cache is not full. Which of the following is the most likely root cause and recommended solution?

Accepted Answer

Cause: vSAN disk group has a single SSD cache leading to high latency during heavy writes. Solution: Convert to all-flash vSAN.. Option C is correct. The high spike latency suggests that the SSD cache is being overwhelmed during write bursts. All-flash vSAN eliminates the HDD tier bottleneck. Option A is wrong; the cache is not full, so adding capacity won't help write bursts; the issue is write buffer exhaustion. Option B is wrong; memory ballooning would cause swapping but not high device latency. Option D is wrong; contention is not from multiple VMs sharing the disk group, as vSAN distributes objects.

Answer

Cause: vSAN cache is unable to handle the write burst. Solution: Add more cache capacity by using larger SSDs.

Answer

Cause: The VM's memory ballooning is causing excessive swapping to vSAN, which is slow. Solution: Increase the VM's memory reservation.

Answer

Cause: vSAN is encountering disk contention due to multiple VMs sharing the same disk. Solution: Deploy a dedicated vSAN datastore for the customer.

Question 11

A vSphere administrator is troubleshooting a VM that hosts a critical database. The VM is configured with 8 vCPUs and 64 GB memory on an ESXi host with two 10-core CPUs (hyperthreading enabled). Performance charts show CPU ready time averaging 12% during peak hours, and the database application is experiencing high transaction latency. The administrator has verified that no other VMs are contending for CPU. Which action will most likely reduce CPU ready time without negatively impacting database performance?

Accepted Answer

Reduce the number of vCPUs assigned to the VM to 4.. Option C is correct because reducing the number of vCPUs to match the actual workload reduces scheduler overhead and improves cache locality. A VM with 8 vCPUs on a host with 40 logical CPUs should not normally have high ready time unless the vCPU count is excessive relative to the workload. Reducing to 4 vCPUs often resolves contention without degrading throughput because many database workloads do not scale linearly beyond 4 vCPUs. Option A is wrong because disabling hyperthreading reduces logical CPUs, potentially increasing contention. Option B is wrong because increasing memory does not affect CPU ready time. Option D is wrong because CPU affinity can lead to unbalanced load and is not a best practice for DRS clusters.

Answer

Disable hyperthreading on the host.

Answer

Assign a CPU affinity mask to pin the VM to specific physical cores.

Answer

Increase the VM's memory reservation.

Question 12

An administrator is analyzing performance data for a vSphere cluster and wants to identify VMs that are experiencing memory pressure. Which two metrics from esxtop or vCenter performance charts reliably indicate that a VM is actively reclaiming memory due to contention? (Choose two.)

Accepted Answer

Ballooned memory. Memory ballooning and swapping are clear indicators of memory pressure. Ballooning occurs when the VMkernel reclaims memory from a VM via the balloon driver, and swapping occurs when the hypervisor is forced to swap pages to disk. Active memory is the currently used memory, not a sign of pressure. Consumed memory includes overhead and target memory. Overhead memory is the hypervisor overhead, not a pressure metric.

Answer

Consumed memory

Answer

Active memory

Answer

Overhead memory

Question 13

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.)

Accepted Answer

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

Configure CPU affinity for VMs with high vCPU counts.

Answer

Increase the DRS migration threshold to the most aggressive setting.

Question 14

A financial services company has a vSphere cluster with four hosts, each equipped with 2 CPU sockets (10 cores each, hyperthreading enabled) and 512 GB RAM. The cluster runs a mix of production and test VMs. Recently, a critical trading application VM (8 vCPUs, 64 GB RAM) was moved by DRS to a host that also runs an analytics workload (4 vCPUs, 32 GB RAM). After the move, the trading application's performance degraded significantly. The administrator checks vCenter performance charts and sees that the trading VM's CPU ready time has increased from 2% to 20% since the migration, while the host's overall CPU utilization is only 50%. The analytics VM shows normal performance. What is the most likely cause of the performance degradation?

Accepted Answer

The trading VM is spanning multiple NUMA nodes on the destination host.. The trading VM is likely spanning multiple NUMA nodes on the destination host. The host has two NUMA nodes (one per socket). With 8 vCPUs, the VM may span both nodes, causing remote memory access latency, which increases CPU ready time indirectly due to memory stalls. Option C directly addresses this. Option A describes a BIOS setting that may be incorrect but is less likely to change after a DRS move. Option B addresses a different issue (memory overcommit). Option D would help but is not the best immediate action; the root cause is NUMA configuration.

Answer

The host has NUMA node interleaving enabled in BIOS.

Answer

The trading VM's CPU affinity is incorrectly set after migration.

Answer

The host has insufficient memory to run both VMs, causing memory overcommitment.

Question 15

A company has a vSphere 7 cluster with 6 hosts, each with 2 sockets (16 cores per socket, hyperthreading enabled) and 1 TB RAM. The cluster uses DRS with a migration threshold of 4 (moderate). A single VM runs a latency-sensitive trading platform with 12 vCPUs and 256 GB RAM. During market hours, the administrator notices that the VM's CPU ready time spikes to 15%, and the application reports high response times. The administrator runs esxtop on the host and sees the following: %RDY for the VM is 15%, %CSTP is low, and the host's overall CPU utilization is 60%. The VM is on a host that also has 5 other VMs with smaller resource footprints. The administrator wants to minimize disruption while improving performance. Which action should the administrator take first?

Accepted Answer

Configure the VM's NUMA node preference to use a single NUMA node.. Trading VMs with high vCPU counts often benefit from NUMA-awareness. The host has 2 NUMA nodes (one per socket). With 12 vCPUs, the VM likely spans both nodes, causing remote memory access. By setting the VM to prefer one NUMA node (or limiting vCPUs to 8), performance improves. Option D is the most effective immediate step. Option A may cause excessive vMotion. Option B might not address the root cause. Option C would reduce parallelism and might not help if the application is multithreaded.

Answer

Manually migrate the VM to a host with fewer running VMs.

Answer

Increase the VM's CPU reservations to guarantee CPU cycles.

Answer

Reduce the VM's vCPU count from 12 to 8.