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VMware Interview Questions and Answers

1) What is VMware and what are their benefits?

VMWare Kernel is a Proprietary Kenral and is not based on any of the UNIX operating systems, it’s a kernel developed by VMWare Company. The VMKernel can’t boot it by itself, so that it takes the help of the 3rd party operating system. In VMWare case the kernel is booted by RedHat Linux operating system which is known as service console. The service console is developed based up on Redhat Linux Operating system, it is used to manage the VMKernel

VMware provides different applications and software for virtualization.  VMware products are categorized in two levels, desktop applications, and Server applications.  It is useful for

– Running multiple operating systems and applications on a single computer

– Consolidate hardware to get vastly higher productivity form fewer servers

2) Mention what are the different types of virtualization available?

Different types of virtualization available are

– Application virtualization

– Presentation virtualization

– Network virtualization

– Storage virtualization

3) what are the different types of server software does VMware provides?

VMware provides three different types of server software

– VMware ESX Server

– VMware ESXi Server

– VMware Server

4) Explain what is hypervisor?

Hypervisor is a program that enables multiple operating systems to share a single hardware host.  Each operating system has the host’s processor, memory and other resources all to itself.  Hypervisor controls the resources and host processor, allocating what is required for each operating system in turn and make sure that the guest operating system cannot disrupt each other.

5) Explain what is VMware DRS?

VMware DRS stands for Distributed Resource Scheduler; it dynamically balances resources across various host under cluster or resource pool.  It enables users to determine the rules and policies which decide how virtual machines deploy resources, and these resources should be prioritized to multiple virtual machines.

6) Explain VMware Fault Tolerance?

VMware fault tolerance is an important component of VMware vSphere, and it offers continuous accessibility to applications by preventing data loss and down time of virtual machines in the event of ESX server failure.

7) what is FT logging traffic?

FT logging is one of the options in VMKernel port setting which is more or less same as enabling vmotion option in the vmkernel port.

8) what are the different components used in VMware infrastructure?

Different components used in VMware infrastructure includes

– It consists of the lowest layer which acts as an ESX server host

– It also uses the virtual center server which keep tracks of all the VM associated images and manage it from one point

– VMWare infrastructure client, it enables the client to communicate with user’s applications that are running on VMware

– Web-browser is used to access the virtual machines

– License server is used to prepare a server which provides licensing to the applications

– Database servers are availed to maintain a database

9) Explain what is vCloud Suite?

vCloud Suite combines with multiple VMware components to give a complete set of cloud infrastructure capabilities in a single package, including virtualization, software-defined datacenter services, disaster recovery, application management, etc.

10) what are the storage and availability in vCloud Suite?

The storage and availability in vCloud Suite includes

– Storage DRS: It place and load balance virtual machines based on storage capacity and I/O latency

– Storage vMotion: It employs proactive, non-disruptive storage migration to reduce virtual machine storage I/O bottlenecks and free up valuable storage capacity

– Application HA: It gains high availability that is bound to specific applications

– Data Protection: Based on EMC avamar, it deploys a back-up and recovery tool

11) Explain what is Host Isolation in VMware HA (High Availability)?

In VMware HA, it has a mechanism to detect a host isolated from the rest of hosts in the cluster.  In simple words, it uses a heart-beat to communicate other host in the cluster. When the ESX host loses its ability to connect with other hosts in a cluster through heart-beat, then ESX host will be considered as a Host Isolation.

12) Mention what is the difference between VMware HA and Vmware FT?

– VMware FT is enabled per VM basis while VMware is enabled per cluster\

– In the case of ESX host failure, virtual machines are the failed host and are re-started and powered-on the other active hosts in HA cluster. But FT enabled virtual machines; there is no down time. In the case of host failure, secondary VM will be activated, and it becomes primary and continue to run from the exact point where the primary VM is failed or left off.

13) Explain the new features available in vSphere 5?

In the latest version of vSphere 5.5 it includes

– ESXi Hypervisor enhancement

– Virtual Machine Enhancement

– VMware vCenter Server Enhancement

– vSphere storage Enhancement

– vSphere Networking Enhancements

14) What are the new features included in ESXi Hypervisor enhancement?

In ESXi Hypervisor enhancement includes

– Hot-pluggable PCIe SSD Devices: It supports SSDs (Solid State Disks) devices, and with a new enhancement, SSD device can be removed or added while a vSphere host is running.

– Support for Reliable Memory Technology: vSphere ESXi hypervisor can take an advantage of new hardware; vendor enabled Reliable Memory Technology, through which a region of memory is reported from the hardware to vSphere ESXi hypervisor. It is used to enhance the placement of VMKernel and other components like initial thread and hostd. It helps to protect against memory error

– Enhancements to CPU C-states: A power process (C-state) is used to provide additional power savings

15) what is the difference between template and clone in VMware?


16) What are the three port groups present in ESX server networking
   1. Virtual Machine Port Group – Used for Virtual Machine Network
2. Service Console Port Group – Used for Service Console Communications
3. VMKernel Port Group – Used for VMotion, iSCSI, NFS Communications
17) What is the use of a Port Group?
The port group segregates the type of communication.
18) What are the type of communications which requires an IP address for sure ?
   Service Console and VMKernel (VMotion and iSCSI), these communications does not happen without an ip address (Whether it is a single or dedicated)
19) In the ESX Server licensing features VMotion License is showing as Not used, why?
    Even though the license box is selected, it shows as “License Not Used” until, you enable the VMotion option for specific vSwitch
20) How the Virtual Machineort group communication works ? 
     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’s

 21) What is a VLAN ?
     A VLAN is a logical configuration on the switch port to segment the IP Traffic. For this to happen, the port must be trunked with the correct VLAN ID.

 22) Does the vSwitches support VLAN Tagging? Why? 
     Yes, The vSwitches 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 VLANtagging 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. :)

 23) What is Promiscuous Mode on vSwitch ? What happens if it sets to Accept?
     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 inteded port, so that the intended virtual machine was able to see the communication.

 24) What is MAC address Changes ? What happens if it is set to Accept ?
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.

 25) What is Forged Transmits ? What happens if it is set to Accept ?
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.

 26) What are the core services of VC ?
VM provisioning , Task Scheduling and Event Logging
 27) Can we do vMotion between two datacenters ? If possible how it will be?
Yes we can do vMotion between two datacenters, but the mandatory requirement is the VM should be powered off.

 28) What is VC agent? and what service it is corresponded to? What are the minimum req’s for VC agent installation ?
VC agent is an agent installed on ESX server which enables communication between VC and ESX server.
The daemon  associated with it is called vmware-hostd , and the service which corresponds to it is called as mgmt-vmware, in the event of VC agent failure just restart the service by typing the following command at the service console

     ” service mgmt-vmware restart “ 
VC agent installed on the ESX server when we add it to the VC, so at the time of installtion if you are getting an error like ” VC Agent service failed to install “, check the /Opt size whether it is sufficient or not.

 29) How can you edit VI Client Settings and VC Server Settings ?
Click Edit Menu on VC and Select Client Settings to change VI settings
Click Administration Menu on VC and Select VC Management Server Configuration to Change VC Settings

 30) What are the files that make a Virtual Machine  ?
     .vmx – Virtual Machine Configuration File
.nvram – Virtual Machine BIOS
.vmdk – Virtual Machine Disk file
.vswp – Virtual Machine Swap File
.vmsd – Virtual MAchine Snapshot Database
.vmsn – Virtual Machine Snapshot file
.vmss – Virtual Machine Suspended State file
.vmware.log – Current Log File
.vmware-#.log – Old Log file

31) What are the devices that can be added while the virtual Machine running
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

32) How to set the time delay for BIOS screen for a Virtual Machine?
Right Click on VM, select edit settings, choose options tab and select boot option, set the delay how much you want.

33) What is a template ?
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 VM’s.
34) What to do to customize the windows virtual machine clone,?
copy the sysprep files to Virtual center directory on the server, so that the wizard will take the advantage of it.

35) What to do to customize the linux/unix virtual machine clone,?
VC itself includes the customization tools, as these operating systems are available as open source.

36) Does cloning from template happens between two datacenters ?
Yes.. it can, if the template in one datacenter, we can deploy the vm from that template in another datacenter without any problem.

37). What are the common issues with snapshots? What stops from taking a snapshot and how to fix it ?

If you configure the VM with Mapped LUN’s, 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 LUN’s as physical, you need to remove it to take a snapshot.

38) What are the settings that are taken into to consideration when we initiate a snapshot ?
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)

40) What are the requirements for Converting a Physical machine to VM ?
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

41) What is VMWare consolidated backup ?
It is a backup framework, that supports 3rd party utilities to take backups of ESX servers and Virtual Machines. Its not a backup service.

42) To open the guided consolidation tool, what are the user requirements ?
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

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