VMware Interview Questions & Answers Part 2

In Series of VMware Interview Questions this is the second part of the series. In this part 2 you will find more VMware Interview Questions related to different features of vSphere. This questions will help you to get more overview about the interview questions and answers of VMware.

In this post we will discuss about VMware interview questions on different features of vSphere such as High availability, Fault Tolerance etc.

If you have not seen our first part of this series then please check below link:

VMware Interview Questions & Answers Part 1

In this post you will find Interview Questions related to various VMware features such as vSphere HA, FT & DRS so that you can easily answer them in your interviews.

ESXi is Type1 or Type2 Hypervisor:
ESXi is a Type1 Bare metal hypervisor because it is installed directly on the physical hardware server. It does not require any Operating system.

What are the ways of Installing ESXi:

• Interactive ESXi installation
• Scripted ESXi installation
• Auto Deploy ESXi installation
• Customizing installations with ESXi Image Builder CLI

What are the ways of Upgrading ESXi:

• vSphere Update Manager
• Interactively using an ESXi installer ISO image
• Scripted upgrade
• vSphere Auto Deploy
• ESXi Command-line interface

What is Customized ESXi ISO:
Customized ESXi ISO are made by the hardware vendors such as HP, DELL, IBM to install ESXi onto their respective hardware. So it includes all the latest and supported drivers and features.

What is DCUI:
The Direct Console User Interface (DCUI) allows you to interact with the host locally using text-based menus. You can use the Direct Console User Interface to enable local and remote access to the ESXi Shell.

What are the ways of accessing ESXi :
ESXi can be accessed using DCUI, vSphere client and vSphere Web Client. ESXi 6.5 and later versions do not support vSphere Client so you can access it using DCUI and vSphere Web Client.

What is Lockdown Mode in ESXi:
When you enable lockdown mode, no users other than “vpxuser” have authentication permissions, nor can they perform operations against the host directly. Lockdown mode forces all operations to be performed through vCenter Server. Lockdown mode can be used to increase the security of ESXi and prevent unauthorized access.

What is maximum number of Snapshots can be used in single Chain ?
Maximum of 32 snapshots are supported in a chain. However, for a better performance use only 2 to 3 snapshots.

What is vCenter Server ?
vCenter Server provides centralized management for the vSphere Infrastructure. It Provides management of ESXi Hosts and Virtual Machines from single console. So you can manage and perform operations on the ESXi and Virtual Machines from using single pane. You can even manage multiple VMware Products from vCenter Server such as NSX, vROPS etc.

What is Difference between vCenter Server for Windows and vCenter Server Appliance ?
vCenter Server for Windows comes as an Windows Installer which requires Windows Server for Installation and has dependency of Windows Server but in case of vCenter Server Appliance you don’t require any Windows Server for Installation, vCenter Server Appliance will be directly deployed on ESXi host as a Virtual Machine.

What is Platform Service Controller ?
Platform Service Controller(PSC) is an very important component of vSphere Infra. PSC allows all VMware products within the same environment can share the authentication domain and other services. Services include certificate management, authentication, and licensing. PSC can be deployed Embedded with vCenter Server or as an External Platform Service Controller.

What is Operating system in vCenter Server Appliance ?
With release of VCSA 6.5 and later vCenter Appliance comes with the Photon Operating System. But previous version of vCenter Server Appliance was using SUSE Enterprise Linux.

Which databases are supported with vCenter Server Appliance 6.7 ?
Below databases are supported with vCenter Server Appliance 6.7:

• Embedded PostgreSQL
• Microsoft SQL Server 2012 SP3
• Microsoft SQL Server 2014 SP2
• Oracle 11g and Oracle 12c

Database supports may change in future versions.

Types of Deployment Supported in vCenter Server :
Below are 3 Types of Deployment supported in vCenter Server:

1. vCenter Server with an embedded Platform Services Controller
2. Platform Services Controller
3. vCenter Server with an external Platform Services Controller (Requires external Platform Services Controller)

What are CPU, Memory and Storage requirements for vCenter Server Appliance 6.7 ?
Below is the chart for CPU, Memory and Storage Requirements of vCenter Server Appliance 6.7:

Which services are in vCenter Server Appliance with Platform Service Controller ?
Below are the services you will find in vCenter Server Appliance:

1. vmware-imagebuilder (VMware Image Builder Manager)
2. vmdird (VMware Directory Service)
3. vmware-analytics (VMware Analytics Service)
4. vmware-mbcs (VMware Message Bus Configuration Service)
5. vsphere-client (VMware vSphere Web Client)
6. vmware-updatemgr (VMware Update Manager)
7. vmware-vapi-endpoint (VMware vAPI Endpoint)
8. vmware-vsan-health (VMware VSAN Health Service)
9. vmware-vsm (VMware vService Manager)
10. vmware-stsd (VMware Security Token Service)
11. lwsmd (Likewise Service Manager)
12. vmdnsd (VMware Domain Name Service)
13. pschealth (VMware Platform Services Controller Health Monitor)
14. vmware-statsmonitor (VMware Appliance Monitoring Service)
15. vmware-sca (VMware Service Control Agent)
16. vmware-sts-idmd (VMware Identity Management Service)
17. vmware-cis-license (VMware License Service)
18. vmware-netdumper (VMware vSphere ESXi Dump Collector)
19. vmware-vpxd-svcs (VMware vCenter-Services)
20. vmware-content-library (VMware Content Library Service)
21. vsan-dps (VMware VSAN Data Protection Service)
22. applmgmt (VMware Appliance Management Service)
23. vmonapi (VMware Service Lifecycle Manager API)
24. vmware-vmon (VMware Service Lifecycle Manager)
25. vmcad (VMware Certificate Service)
26. vmware-rbd-watchdog (VMware vSphere Auto Deploy Waiter)
27. vmware-vcha (VMware vCenter High Availability)
28. vmware-vpostgres (VMware Postgres)
29. vmware-pod (VMware Patching and Host Management Service)
30. vmware-perfcharts (VMware Performance Charts)
31. vmware-vpxd (VMware vCenter Server)
32. vmcam (VMware vSphere Authentication Proxy)
33. vmware-eam (VMware ESX Agent Manager)
34. vmware-postgres-archiver (VMware Postgres Archiver)
35. vmware-rhttpproxy (VMware HTTP Reverse Proxy)
36. vmafdd (VMware Authentication Framework)
37. vsphere-ui (VMware vSphere Client)
38. vmware-cm (VMware Component Manager)
39. vmware-sps (VMware vSphere Profile-Driven Storage Service)

What is vCenter Server Enhanced Linked Mode ?

vCenter Enhanced Linked Mode allows you to log in to any single instance of vCenter Server Appliance or vCenter Server and view and manage the inventories of all the vCenter Server systems in the group.
You can join up to ten vCenter Server Appliance systems and eight vCenter Server systems with vCenter Enhanced Linked Mode.

What is the latest version of VMFS ?
Latest version of VMFS is VMFS 6.

Difference between VMFS 5 & VMFS 6 :

Above table is taken from VMware Documentation.

What is Permanent Device Loss:
It occurs when Storage Device this indicates that the device is permanently inaccessible to the ESXi host, or is in a Permanent Device Loss (PDL) state. The ESXi host no longer attempts to re-establish connectivity or issue commands to the device. You can identify it by SCSI sense code of “H:0x0 D:0x2 P:0x0 Valid sense data: 0x5 0x25 0x0 or Logical Unit Not Supported” in VMkernel logs.

What is All Paths Down :
All-Paths-Down (APD) situation occurs when all paths to a device are down. As there is no indication whether this is a permanent or temporary device loss, the ESXi host keeps reattempting to establish connectivity. APD-style situations commonly occur when the LUN is incorrectly unpresented from the ESXi/ESX host. The ESXi/ESX host, still believing the device is available, retries all SCSI commands indefinitely. This has an impact on the management agents, as their commands are not responded to until the device is again accessible. This causes the ESXi/ESX host to become inaccessible/not-responding in vCenter Server.

What is RDM:
An RDM is a mapping file in a separate VMFS volume that acts as a proxy for a raw physical storage device. With the RDM, a virtual machine can access and use the storage device directly. The RDM contains metadata for managing and redirecting disk access to the physical device. The file gives you some of the advantages of direct access to a physical device, but keeps some advantages of a virtual disk in VMFS. As a result, it merges the VMFS manageability with the raw device access.

What are RDM Compatibility Modes:
You can use RDMs in virtual compatibility or physical compatibility modes. Virtual mode specifies full virtualization of the mapped device. Physical mode specifies minimal SCSI virtualization of the mapped device, allowing the greatest flexibility for SAN management software.

RDM Virtual Compatibility Mode:
In this mode the VMkernel sends only READ and WRITE to the mapped device. The mapped device appears to the guest operating system exactly the same as a virtual disk file in a VMFS volume. The real hardware characteristics are hidden. If you are using a raw disk in virtual mode, you can realize the benefits of VMFS such as advanced file locking for data protection and snapshots for streamlining development processes. Virtual mode is also more portable across storage hardware than physical mode, presenting the same behavior as a virtual disk file.

RDM Physical Compatibility Mode:
In this mode the VMkernel passes all SCSI commands to the device, with one exception: the REPORT LUNs command is virtualized so that the VMkernel can isolate the LUN to the owning virtual machine. Otherwise, all physical characteristics of the underlying hardware are exposed. Physical mode is useful to run SAN management agents or other SCSI target-based software in the virtual machine. Physical mode also allows virtual-to-physical clustering for cost-effective high availability.

Which Protocols are Supported for VCSA Backup :
Below are the Protocols supported in vCenter Appliance Backups

• FTP
• FTPS
• HTTP
• HTTPS
• SFTP
• NFS
• SMB

What is Heartbeating in vSphere HA ?
Heartbeating is used by vSphere to identify whether the ESXi host is alive and working.

Which 2 types of Heartbeats are used by vSphere HA ?
vSphere HA uses Network Heartbeating and Datastore Heartbeating.

What is Election Process in vSphere HA ?
When you configure vSphere HA on the cluster there is Election happens in the background which decides who will be Master Host and who are the Slave Hosts. Election Process takes approx 15 seconds and conducted using UDP.

How Election Process works in vSphere HA ?
The election process is simple but robust.The host that is participating in the election with the greatest number of connected datastores will be elected master. If two or more hosts have the same number of datastores connected, the one with the highest Managed Object Id will be chosen. This however is done lexically; meaning that 99 beats 100 as 9 is larger than 1. So whoever host is having Managed Object ID 99 will be elected as Master.

What is Master & Slave in vSphere HA ?
Master Host is the elected one in the Election process and Slave Hosts are the other hosts which comes under Master Host and monitored by Master Host

Master Host :
Master Host will have all the data of Slave Hosts and Virtual Machines running on them. The master uses this protectedlist file to store the inventory. It keeps track of the state of the virtual machines & it is responsible for and to take action when appropriate. Master host also decides which virtual machines needs to be restarted based on the situation of Slave host failure.

Slave Host :
Slave hosts are the hosts which are monitored by master. Slave host monitors the virtual machines running on them. The slave also monitors the health of the master by monitoring heartbeats. If the master becomes unavailable, the slaves initiate and participate in the election process. slaves sends heartbeats to the master so that the master can detect outages.

What is Fault Tolerance ?
Fault Tolerance is referred as FT in VMware. FT works on the VM level. VMware Fault Tolerance provides continuous availability for virtual machines by creating and maintaining a Secondary VM that is identical to, and continuously available to replace, the Primary VM in the event of a failover situation. The protected virtual machine is called the Primary VM. The duplicate virtual machine, the Secondary VM, is created and runs on another host.

Which Locking Technology is used by VMware FT ?
VMware FT uses Atomic file locking on shared storage which is used to coordinate failover so that only one side continues running as the Primary VM and a new Secondary VM is respawned automatically. It avoids Split Brain situation by using this Technology.

What is Licensing Limits in VMware Fault Tolerance ?
VMware FT on Standard License supports up to 2vCPU & on Enterprise Plus License supports up to 8 vCPUs. (This data is for vSphere 6.7 it might differ in different versions.)

What is DRS ?
DRS is Distributed Resource Scheduler which works on the Cluster level. DRS monitors the CPU & Memory of the ESXi Hosts to monitor the Load. DRS continuously monitors load on the ESXi hosts and tries to balance the load by migrating Virtual Machines within the cluster. DRS has 3 different modes: Fully Automated, Partially Automated & Manual.

What are the DRS Rules ?
DRS comes with the 2 types of Rules. Where you can creates VM-VM & VM-Host rules.
VM-VM rule specify that 2 VMs together Should or Must run on the same ESXi host.
VM-Host rule specify that VM should or Must run on the specified ESXi host only.
You can create VM & Host groups to be used with this rules.

What is the use of Update Manager ?
Update Manager is used to Patch of Upgrade the ESXi hosts in your vSphere Infrastructure. Update Manager also can be used to Upgrade VMware Tools & VM Hardware Versions of Virtual Machines. Update Manager allows you to create Baseline check Host compliant and then Remediate the ESXi hosts.

What is the Process of Upgrading vSphere Components or Infrastructure ?
Below is the process for upgrading your vSphere Infrastructure:

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Checkout Part one of our VMware Interview Questions: Top VMware Interview Questions

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Information source : VMware Documentation.