Top 50 Vmware Interview Questions You Must Prepare 29.Nov.2023

  • In VI 3.5 we can add Hard Disk and NIC's while the machine running.
  • In vSphere 4.0 we can add Memory and Processor along with HDD and NIC's while the machine running.

ISCSI datastores, FC SAO datastores, Local VMFS, NAS and NFS.

Happened when SAN went down. Raid controller was bad. Had to restore VM. Also when a thin provisioned server used almost all of the vmfs volume. Had to move some old powered off VM from VMFS Volume.

It depends on the size of the VMs and the performance of the storage. Higher performing storage can be filled to capacity but space should be left for data growth and snapshots. A datastore should never be allowed to fill up 100%.

VM Provisioning: Virtual Machine Creation.

Alarms & Event Management:

  • Alarms are used to know the status of the resource usage for a VM.
  • Events are used monitor the tasks that are taken place on the esx servers or in the virtual center.

Task Scheduler: Task scheduler, if you want to schedule a task it will be used, for example if you want move one vm from one host to another host or if you want shutdown/reboot a vm etc.

Hardware Compatibility List: what is the hardware that compatible with ESX OS.

A set of best practice configuration rules, which are can be applied to entire cluster or to an individual host. So that all the hosts in sync with each other, this will avoid vMotion, drs and ha problems.

HA & DRS are the properties of a Cluster. A Cluster can be created only when more than one host added, in that case we need to configure HA & DRS as well to provide High Availability and Load balancing between hosts and for the virtual machines.

VMware HA provides high availability for virtual machines by pooling them and the hosts they reside on into a cluster. Hosts in the cluster are monitored and in the event of a failure, the virtual machines on a failed host are restarted on alternate hosts.

Addressing Scheme, iSCSI relies on IP and FC not, and the type of transfer of data also. In FC the data transferred as blocks, in iSCSI the data transferred as files. The cabling also, FC uses Fibre cable and iSCSI uses RJ45.

  • An agent needs to be installed on the Physical machine.
  • VI client needs to be installed with Converter Plug-in.
  • A server to import/export virtual machines.

Right Click on VM, select edit settings, choose options tab and select boot option, set the delay how much you want.

No. Only starting with ESX/ESXi 4.0.

Even though the license box is selected, it shows as "License Not Used" until, you enable the VMotion option for specific vSwitch.

Exchange server and Share Point, but these are for DEMO purposes, Citrix presentation servers etc.

If the promiscuous mode set to Accept, all the communication is visible to all the virtual machines, in other words all the packets are sent to all the ports on vSwitch.

If the promiscuous mode set to reject, the packets are sent to intended port, so that the intended virtual machine was able to see the communication.

VC itself includes the customization tools, as these operating systems are available as open source.

For better resource management as it has a virtualization layer involved in its kernel, which communicates with the hardware directly.

We can convert a VM into Template, and it cannot be powered on once its changed to template. This is used to quick provisioning of VMs.

False. A Distributed Virtual Switch acts as a single switch across all hosts in a data center to provide centralized provisioning, administration, and monitoring of virtual networks.

Yes, then Switches support VLAN Tagging; otherwise if the virtual machines in an esx host are connected to different VLANS, we need to install a separate physical nic (vSwitch) for every VLAN. That is the reason Vmware included the VLAN tagging for vSwitches. So every vSwitch supports upto 1016 ports, and BTW they can support 1016 VLANS if needed, but an ESX server doesn’t support that many VM’s. :)

No, because Host Profiles was designed with the generic vNetwork Distributed Switch. The Cisco Nexus 1000v switch gives administrators fine-grained control of the networking beyond what Host Profiles can apply.

When and why should you give a vm multiple vCPUs part of their answer would be that best practice is to start with a single vCPUs because of you can run into performance issues due to CPU scheduling.

It's a clustered file system, excellent support for sharing between ESX servers in a cluster.


  • Allows access by multiple ESX Servers at the same time by implementing profile locking. SCSI Reservations are only implemented when LUN meta data is updated (e.g. file name change, file size change, etc.)
  • Add or delete an ESX Server from a VMware VMFS volume without disrupting other ESX Server hosts.
  • LVM allows for adaptive block sizing and addressing for growing files allows you to increase a VMFS volume on the fly (by spanning multiple VMFS volumes) With ESX/ESXi 4 VMFS volumes also can be expanded using LUN expansion Optimize your virtual machine I/O with adjustable volume, disk, file and block sizes. Recover virtual machines faster and more reliably in the event of server failure with Distributed journaling.


Can be shared with up to 32 ESX Servers. Can support LUNs with max size of 2TB and a max VMFS size of 64 TB as of version 4 (vSphere). "There is a VMFS3 limitation where each tree of linked clones can only be run on 8 ESX servers. For instance, if there is a tree of disks off the same base disk with 40 leaf nodes in the tree, all 40 leaf nodes can be simultaneously run but they can only run on up to 8 ESX hosts." VMFS3 limits files to 262,144 (218) blocks, which translates to 256 GB for 1 MB block sizes (the default) up to 2 TB for 8 MB block sizes.

Service Console and VMKernel (VMotion and iSCSI), these communications does not happen without an ip address (Whether it is a single or dedicated).

Storage can be added via iSCSI, FC, NFS and local disk (including DAS).

Storage team will provide the LUN information, with that we will add those LUNs to ESX hosts from VM storage.

Copy the sysprep files to Virtual center directory on the server, so that the wizard will take the advantage of it.

A cluster is a group of servers working together closely as a single server, to provide high availability, load balancing and high performance. A host is a single x86 computing server with individual computing and memory resources. Resource pools are allocation of the available resources in to pieces for the proper distribution.

The port group segregates the type of communication.

The user must be member of administrator, the user should have "Logon as service" privileges - To give a user these privileges, open local sec policy, select Logon as service policy and add the user the user should have read access to AD to send queries.

All the vm's which are configured in VM Port Group are able to connect to the physical machines on the network. So this port group enables communication between vSwitch and Physical Switch to connect vm's to Physical Machine.

  • Virtual Machine Configuration (What hardware is attached to it).
  • State of the Virtual Machine Hard Disk file ( To revert back if needed).
  • State of the Virtual Machine Memory (if it is powered on).

If the promiscuous mode is enabled for a switch, the traffic sent that switch will be visible to all vm's connected to that switch. I mean, the data will be broadcasted.

  • If you configure the VM with Mapped LUN, then the snapshot failed. If it is mapped as virtual then we can take a snapshot of it.
  • If you configure the VM with Mapped LUNs as physical, you need to remove it to take a snapshot.

Using the Virtual Infrastructure Client we can manage one esx server, using virtual center we can manage more than 1 esx server. And also we can use service console to manage it.

Yes. It can, if the template in one datacenter, we can deploy the vm from that template in another datacenter without any problem.

  • Yes, but remember to use an ESX host and not an ESXi host to create a profile for use.
  • In theory, Host Profiles should work with mixed host clusters, as it translates ESX to ESXi, but be careful as there are enough differences between ESX and ESXi that can lead you to make self-inflicted errors when applying Host Profiles. The easiest method is to create clusters that are homogeneous and maintain two different profiles for these two types of clusters.

Either by creating separate vSwitches using dedicated NICs or if NICs are not available by creating separate port groups using different VLAN IDs on the same vSwitch.

Always have a backup of the VMs on a separate storage environment that can be used to restore the lost virtual servers.

A resource pool is a logical abstraction for flexible management of resources. Resource pools can be grouped into hierarchies and used to hierarchically partition.

When we create a virtual machine the configuration wizard generates a MAC address for that machine, you can see it in the .vmx (VM Config) file. If it doesn't matches with the MAC address in the OS this setting does not allow incoming traffic to the VM. So by setting Reject Option both MAC addresses will be remains same and the incoming traffic will be allowed to the VM.

A VMware ESX Resource pool is a pool of CPU and memory resources. Inside the pool, resources are allocated based on the CPU and memory shares that are defined. This pool can have associated access control and permissions. Clear management of resources to the virtual machines.

When we create a virtual machine the configuration wizard generates a MAC address for that machine, you can see it in the .vmx (VM Config) file. If it doesn't matches with the MAC address in the OS this setting does not allow outgoing traffic from the VM. So by setting Reject Option both MAC addresses will be remains same and the outgoing traffic will be allowed from the VM.

A typical VMware Infrastructure data center consists of basic physical building blocks such as x86 computing servers, storage networks and arrays, IP networks, a management server and desktop clients.

VMware Consolidated Backup is a backup framework, which enables 3rd party tools to take backups.

VCB is used to help you backup your VMware ESX virtual servers. Essentially, VCB is a "backup proxy server". It is not backup software. If you use VCB, you still need backup software. It is commonly installed on its own dedicated Windows physical server.

Here are the benefits of VMware's VCB:

  • Centralize backups of VMware ESX Virtual Servers.
  • Provide file level backups of VMware ESX Virtual Servers both full and incremental (file level backup available to only Windows guests).
  • Provide image level backups.
  • Prevent you from having to load a backup agent on every Virtual Machine.
  • Prevent you from having to shutdown Virtual Machines to get a backup.
  • Provides LANFree backup because the VCB server is connected to the SAN through your fibre channel adaptor.
  • Provides centralized storage of Virtual Server backups on the VCB server that is then moved to your backup tapes through the 3rd party backup agent you install.
  • Reduces the load on the VMware ESX servers by not having to load a 3rd party backup agent on either the VMware ESX service console or on each virtual machine.
  • Utilizes VMware Snapshots.

Basically, here is how VCB works:

  • If you are doing a file level backup, VCB does a snapshot of the VM, mounts the snapshot, and allows you to backup that mounted "drive" through VCB to your 3rd party backup software.
  • If you are doing an image level backup of the VM, VCB does a snapshot of the VM, copies the snapshot to the VCB server, unsnaps the VM, and allows you to backup the copied snapshot image with your 3rd party backup software.

If we have FC cards installed on the esx servers, by going to the storage option, we can scan for the lungs.

A set of best practice configuration rules, which are can be applied to entire cluster or to an individual host. So that all the hosts in sync with each other, this will avoid vMotion, drs and ha problems.

It is a backup framework that supports 3rd party utilities to take backups of ESX servers and Virtual Machines. It’s not a backup service.

ESX is an OS with full features of virtualization; ESXi is a limited features OS with 32MB image.