What are the key files that make up a virtual machine, and what does the .vmx file represent?

A virtual machine consists of several files stored on a storage device. Key files include:

• .vmx: The virtual machine configuration file.
• .vmdk: Describes virtual disk characteristics.
• -flat.vmdk: The actual data disk.
• .nvram: Stores BIOS or EFI configuration.
• .vswp: The virtual machine swap file.
• .log: The current log file (vmware.log).

What is the difference between OVF and OVA file formats when deploying templates?

OVF (Open Virtual Machine Format) is an open standard that contains multiple files as a package (e.g., .ovf, .vmdk, .nvram). OVA (Open Virtual Appliance) is a single-file distribution of the OVF file package. Both formats are compressed for faster downloads and support the exchange of virtual appliances across products and platforms. ,

What is the primary purpose of VMware Tools?

VMware Tools is a suite of utilities that enhances the performance of the virtual machine guest operating system and improves the management of the VM. It includes essential device drivers and other software that allow you to have more control over the virtual machine interface, such as managing power controls and synchronizing time between guest and host. ,

How does a Content Library assist in managing virtual machine templates?

Content libraries are container objects for VM and vApp templates and other files (like ISOs). They allow you to share content across vCenter instances in the same or different locations. Sharing templates through libraries results in consistency, compliance, efficiency, and automation when deploying workloads at scale.

What is the difference between “Cold Migration” and “Hot Migration” (vMotion)?

• Cold Migration: Moving a powered-off or suspended virtual machine to a new host or datastore.
• Hot Migration (vMotion): Moving a powered-on virtual machine to a new host or datastore without interrupting its availability. ,

Can you add hardware resources to a VM while it is running?

Yes, if the “Memory hotplug” or “CPU hotplug” options are enabled in the VM settings. This allows you to add memory or CPU resources while the VM is running. However, the guest operating system must also support this feature.

What is a “Template” in vSphere, and can you modify it after creation?

A template is a primary copy of a virtual machine used to create and provision new VMs. You cannot modify a template while it is a template. To alter it, you must convert it to a virtual machine, make the changes, and convert it back to a template. ,

What are the three main types of vMotion based on resource changes?

1. Change compute resource only: Moving the VM to another host/cluster but keeping storage the same.
2. Change storage only (Storage vMotion): Moving the VM’s storage to a new datastore while it remains on the same host.
3. Change both compute resource and storage: Moving the VM to a new host and its disks to a new datastore simultaneously.

Explain the “Instant Clone” technology mechanism. What happens to the source VM during the process?

Instant Clone creates a powered-on VM from the running state of another powered-on source VM. During the operation, the source VM is “stunned” for a short period (less than 1 second). While stunned, a new writable delta disk is generated for each virtual disk, and a checkpoint is taken and transferred to the destination VM. The destination VM powers on using this checkpoint. Instant Cloned VMs are fully independent vCenter inventory objects. ,

When configuring Per-VM EVC (Enhanced vMotion Compatibility), what are the prerequisites, and how does it interact with Cluster-level EVC?

• Prerequisites: The VM must be powered off to change the mode, and the virtual hardware version must be 14 or later.
• Interaction: Per-VM EVC determines the CPU features a VM requires to power on. If configured, Per-VM EVC overrides the cluster-based EVC. However, if a VM is in an EVC cluster, the Per-VM EVC mode cannot exceed the cluster’s EVC mode (it cannot require features the cluster hosts mask out). ,,

What is the “Custom EVC Mode” introduced in vSphere 9.0, and how is it defined?

Unlike pre-defined EVC modes that match specific CPU generations, Custom EVC Mode allows you to select a specific set of hosts or clusters. vCenter then constructs a custom EVC mode based on the highest set of CPU and vSGA (Virtual Shared Graphics Acceleration) features that are common to all the selected hosts/clusters.

Describe the vMotion Notification mechanism introduced in vSphere 8.0 for latency-sensitive applications.

It allows an application inside the guest OS to be notified before a vMotion starts. You must set vmx.vmOpNotificationToApp.enabled to true and configure vmx.vmOpNotificationToApp.timeout to specify how long vCenter waits for an acknowledgement. vMotion pauses after generating the start event and waits for the application to acknowledge or for the timeout to expire before proceeding. ,

When migrating a VM with NVIDIA vGPU using vMotion, what is the significance of the “Stun Time Limit”?

vGPU vMotion involves a stun time while the VM is inaccessible. Starting with vSphere 8.0 Update 2, you can set a vMotion Stun Time Limit (in seconds) per VM. If the estimated maximum stun time for the migration exceeds this configured limit, vCenter will prevent the migration or power-on to avoid application timeouts. ,

You need to isolate cold migration, cloning, and snapshot traffic from management traffic. How do you achieve this?

You must create a dedicated VMkernel adapter and assign it to the Provisioning TCP/IP stack. This allows you to assign a dedicated default gateway, routing table, and DNS configuration specifically for provisioning traffic (cold migration, cloning, snapshots), isolating it from the default management stack. ,,

15. Q: What are the specific limitations when cloning a VM that has virtual PMem (vPMem) hard disks versus a VM with an NVDIMM device?

• NVDIMM: If the source VM has an NVDIMM device, the destination host/cluster must have available PMem resources; otherwise, the task fails.
• vPMem Hard Disks (no NVDIMM): If the destination host lacks PMem resources, the operation does not fail. Instead, all hard disks will use the storage policy and datastore selected for the configuration files (standard storage) rather than PMem. ,

When exporting an OVF template that contains a vTPM placeholder, what security consideration is noted regarding the secrets?

When exporting an OVF with a vTPM placeholder, the OVF descriptor contains a placeholder for a vTPM device that does not have any secrets. The virtual machine encryption keys are generated new when you deploy a virtual machine from this OVF template; the original secrets are not exported.

Explain the behavior of CPU compatibility checks during a Cold Migration of a powered-off VM.

CPU compatibility checks generally do not apply when migrating powered-off VMs. The only exception is if you attempt to migrate a powered-off VM configured with a 64-bit OS to a host that does not support 64-bit operating systems; in this case, vCenter generates a warning. ,

What are the three states available for “Encrypted vSphere vMotion,” and what does “Opportunistic” imply?

1. Disabled: Do not use encrypted vMotion.
2. Opportunistic: Use encrypted vMotion if both the source and destination hosts support it; otherwise, fall back to unencrypted vMotion.
3. Required: Allow only encrypted vMotion. If the source or destination does not support it, the migration fails. ,

To enable vMotion for vGPU-powered virtual machines, what specific advanced vCenter setting must be configured?

You must set the vCenter advanced setting vgpu.hotmigrate.enabled to true.

When using Advanced Cross vCenter vMotion to export virtual machines, what is the minimum vCenter version required for the source instance?

To export virtual machines to other vCenter instances using Advanced Cross vCenter vMotion, the source vCenter instance must be version 7.0 Update 1c or later. ,

How does vSphere 7.0 Update 2 and later handle vMotion bandwidth on high-speed links (25 GbE+) compared to older versions?

In vSphere 7.0 Update 1 or earlier, vMotion saturates 1 GbE and 10 GbE physical NICs with a single vMotion VMkernel NIC. Starting with vSphere 7.0 Update 2, vMotion is optimized to saturate high-speed links such as 25 GbE, 40 GbE, and 100 GbE with a single vMotion VMkernel NIC.

When cloning a VM, how does the “Configure per disk” option affect Persistent Memory (PMem) hard disks?

You can use the “Configure per disk” option to convert a PMem hard disk to a regular standard hard disk (though this may cause performance issues). Conversely, you can also convert a standard hard disk to a PMem hard disk during the cloning process.

If you migrate a VM with Storage vMotion and select a new storage policy, how are PMem hard disks handled compared to non-PMem disks?

If you select a new storage policy during Storage vMotion, the new policy only applies to non-PMem hard disks. PMem hard disks are automatically migrated to the host-local PMem datastore of the destination host; they do not follow the standard storage policy. ,

What is the “virtual watchdog timer” device, and what is its function?

It is a virtual device that ensures self-reliance related to system performance within a VM. If the guest OS stops responding and cannot recover due to software glitches, the watchdog timer waits for a predefined period and then restarts the system.

When migrating a VM across vCenter instances, how is MAC address duplication prevented?

The environment specifically handles MAC address migration. vCenter checks the destination vCenter’s target network. If the source VM’s MAC address is generated by the source vCenter, it is categorized as “reserved” on the target to prevent other VMs from grabbing it. If the target vCenter manages the same MAC range and has already assigned that MAC to another VM, the migration is blocked to avoid duplication.