Thursday 25 September 2014

Windows Administrator Interview Questions

Windows Administrator Interview Questions


1. Q: What does Active Directory mean?

A: The active Directory means a service that identifies and handles resources, making them visible for different groups or members that are authorized. It has the role of an object store. The Active directory sees as objects workstations, people, servers devices or documents and they all have their own characteristics and access control list or ACL.
 2.Q: What is the meaning of Global Catalog?
A: A Global Catalog is something that each domain has, and it is used for authenticating the user on the network, on windows 2000 network logon’s were protected from failures by assigning a Global Catalog to every site.
 3.Q: What is the use for DHCP?
A: DHCP is used for the DHCP servers, personal computers can get their configuration from a DHCP server on an IP configuration. The server knows nothing about the personal computers until they make a request for information. Usually the most common information sent is IP address and DHCP is used to make a large network administration easier.
 4.Q: What does a Super Scope do in DHCP?
A: The Super Scope gives the DHCP server the possibility to have leases to multiple clients on the same physical network. The leases come from multiple scopes. All scopes must be defined using DHCP manager before the Super Scope creation and they are named member scopes. The DHCP problems can be resolved by the Super Scope in different ways like the following:
a) on a physical network like a LAN network where multiple logical IP networks exist Super Scope is very useful here. These types of networks are also named multinets.
b) there is also need for a Super Scope when the address pool for the current scope becomes empty and there is a need for new computers on the physical network.
c) when clients have to move on another scope.
d) when DHCP clients from the other side of the relay agents (BOOTP) or the network has many logical subnets.
e) when standard networks are limited to leasing addresses for the clients.
5.Q: How can we switch the roles in an Active Directory?
A: Switching or transferring roles in an Active Directory can be made with the use of Ntdsutil.exe.
 6.Q: What is the purpose of a Stub zone DNS?
A: The copy of a zone that has only the needed resources for finding the authoritative DNS servers in that specific zone (DNS= Domain Name Servers) is called a Stub zone. It also resolves names for DNS namespaces, thing required when names must be resolved from two different DNS namespaces. The Stub zone contains: the master server’s IP that is used for updating the Stub zone and the SOA (Start of Authority), the NS (name server) and the glue A delegated zone records.
 5.Q: What main file is used for Active Directory backup and how it is made?
A: Active Directory backup is made using NTbackup utility. The backup is made once with the system state and they are restored also together because they depend on each other. The system state has different components like:
a)    The registry
b)    Boot files or startup files (files required by the operating system to start).
c)    The component services
d)    The system volume or the SYSVOL folder this is a folder that contains files that are shared on a domain.
e)    The Active Directory
 6.Q: Does a windows administrator have to be critical?
A: Yes and I can explain how. A system administrator is responsible for an entire network which means he/she must take care of multiple things in the same time which is not an easy task. In order to achieve this, an administrator must have high organization skills and a high technical knowledge and he/she must prevent the problems from happening so that he/she won’t have to be forced to fix them.
 Complicated Windows System Administrator Interview Questions
 7.Q: In what way is forward lookup zone different from the reverse lookup zone in NDS?
A: There is one difference between these two: the forward lookup means name to IP and reverse lookup means IP to name.
 8.Q: As a system administrator can you make backup and recovery of data?
A: This is a responsibility that any system administrator must have assume as a basic skill. Of course there are many types of backup that can be made but all must be known for a successful career.
 9.Q: What is the meaning of DHCP and  what is the port used by it to work?
A: DHCP or Dynamic Host Configuration Protocol has the ability to assign an IP automatically, this is done in fact by the server and has a number range. When the system starts an IP is assigned automatically. The DHCP server has port number 68, while the client has 67.
 10.Q: Can you ensure an updated system all the time and perform market research?
A: Staying up-to-date is another strong point of a professional administrator, technology evolves and we must keep up with the flow, otherwise we can’t do our job in a professional way. Market research is the key to an up-to –date work.
 11.Q: Is it possible for a computer to be able to browse the internet without having a default gateway?
A: Yes it is as long as we use a public IP address. The gateway is required as a router or firewall when using an intranet address.
 12.Q: What are the advantages or disadvantages  of using DHCP?
A: The advantage is that the DHCP server configures all IP’s automatically and the disadvantage is that when you receive a new IP address the machine name remains the same because of its association with the IP. It’s not a real problem but when somebody tries to access the machine by its name it become one.
 13.Q: Are you familiar with monitoring?
A: Yes, monitoring is a base activity of a system administrator, he/she manages all the access rights and the server space, security of the user accounts is one of the most important things here. Also an administrator must make sure that the user’s activity doesn’t affect in any way the integrity of the server.
 14.Q: How can we create a SRV record in DNS?
A: To do this we must open the DNS then we must select the abc.local domain the right click and we must go to Other New Records and the SRV ( choose location).
 15.Q: In how much time are the security changes applied on the domain controllers?
A: Including policies for personal and public lockout, the changes apply immediately. The changes also include passwords and LSA or Local Security Authority.
 16.Q: What do you do if a an end user states that a file is gone?
A: Files are deleted constantly by end users but the backup can restore them. Anyhow before using the backup we must check if the user didn’t move the file by mistake in another place.
 Senior level Windows System Administrator Interview Questions
 17.Q: Where is the storage place of the environmental settings and documents from the roaming profile?
A: These documents and settings are deposited locally until the user’s log off, when they are moved into the shared folder from the server so the log on at a fresh system may take a while because of this.
 18.Q: What are the classes that we can find in the Active Directory of Windows Server 2003?
A: We can find:
a)    the abstract class which can be made to look like a template and create other templates, no matter if they are abstract, auxiliary or structural.
b)    the structural class is the important type of class that is made from multiple abstract classes or an existing structural class. They are the only ones that can make Active Directory objects.
c)    the auxiliary class is used as a replace for many attributes of a structural class, it is a list of attributes.
d)    The 88 class is used for objects classes that were defined before 1993 and it is not a common class, it doesn’t use abstract, structural or auxiliary classes.
 19.Q: When is a good time for creating a forest?
A: Certain companies that have different bases require different trees and separate namespaces. And unique names sometimes give birth to different identities of DNS. Also companies are sometimes acquired and get under other influences but the continuity must be preserved for the names.
 20.Q: Can you explain to us about you experience in the past regarding windows administration?
A: I have ten years of experience in this field, I was passionate about computers since childhood and I installed many operating systems at home and inside organizations including these versions of windows: 95, 98, 98 SE, NT, Millenium, 2000, 2003 Server, XP, Seven, Vista. I also managed these systems and performed maintenance, I worked with different applications from the windows environment.
 21.Q: How can you handle a situation in which for instance if you have an application that is not running on Windows 2003 because it’s older?
A: In this situation the application has to be started in the compatibility mode with a previously windows operating system. This is made by right clicking the application icon and choosing another Windows from the compatibility menu.
 22.Q: What is the meaning of Repadmin.exe from Windows Server 2008?
A: Repadmin.exe means Replication Diagnostics Tool and helps for the diagnostic of domain controllers in the Windows system. This tool is used by administrators to see the replication topology from the perspective of every domain controller. The active Directory forest can also be supervised by Repadmin.exe and replication problems can be tracked.
 23.Q: What difference can we find in the usage of CSVDE versus LDIFDE?
A: CSVDE and LDIFDE are both commands and are used for importing and exporting objects but they are different in the way that CSVDE uses the format CSV (Comma Separated Value) which is an Excel file for files and LDIFDE uses LDIF (LDAP Data Interchange Format) file type which can be viewed with a simple text editor. LDIFDE can be also used for editing or deleting objects unlike CSVDE.
 24.Q: What big differences exist between these two operating systems: Windows 2000 and Windows XP?
A: Windows 2000 has more capabilities than Windows XP especially regarding features like DHCP, Terminal Services or DNS. It has all the advantages for server usage. Windows 2000 is a little more professional than XP, but they are both coming with different versions for every user taste. While XP has Home version, Professional or Enterprise, Windows 2000 has Professional and Server editions. The Home version of XP comes with minimal features because the target clients are beginners.
 25.Q: What are the things that make Unix different from Windows?
A: The code loading runtime of Unix is different from the one that Windows has. We must become aware of how the system exactly works before we make a dynamically loading module. Unix has the shared objects with the .so extension that encapsulate lines of code that the programs will use and the functions names. These function names become the references of those functions  in the memory of the program when the file is combined with the program. In Windows the .dll file (dynamic-link library file) doesn’t have references and the code of the files does not link to the memory of the program but they get through a lookup table which points to data or functions. Unix has just one type of library file, with the .a extension and the code of many object file is contained within with the .o extension. When the link is created for a shared object file the definition of the identifier may not be found, so the object code from the library will be included

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Windows admin interview questions

Describe how the DHCP lease is obtained.
It’s a four-step process consisting of (a) IP request, (b) IP offer, © IP selection and (d) acknowledgement.

I can’t seem to access the Internet, don’t have any access to the corporate network and on ipconfig my address is 169.254.*.*. What happened?
 The 169.254.*.* netmask is assigned to Windows machines running 98/2000/XP if the DHCP server is not available. The name for the technology is APIPA (Automatic Private Internet Protocol Addressing).

We’ve installed a new Windows-based DHCP server, however, the users do not seem to be getting DHCP leases off of it.
 The server must be authorized first with the Active Directory.

How can you force the client to give up the dhcp lease if you have access to the client PC?
ipconfig /release

What authentication options do Windows 2000 Servers have for remote clients?
PAP, SPAP, CHAP, MS-CHAP and EAP.

What are the networking protocol options for the Windows clients if for some reason you do not want to use TCP/IP?
NWLink (Novell), NetBEUI, AppleTalk (Apple).

What is binding order?
The order by which the network protocols are used for client-server communications. The most frequently used protocols should be at the top.

How do cryptography-based keys ensure the validity of data transferred across the network?
Each IP packet is assigned a checksum, so if the checksums do not match on both receiving and transmitting ends, the data was modified or corrupted.

Should we deploy IPSEC-based security or certificate-based security?
They are really two different technologies. IPSec secures the TCP/IP communication and protects the integrity of the packets. Certificate-based security ensures thevalidity of authenticated clients and servers.

What is LMHOSTS file?
 It’s a file stored on a host machine that is used to resolve NetBIOS to specific IP addresses.

What’s the difference between forward lookup and reverse lookup in DNS?
Forward lookup is name-to-address, the reverse lookup is address-to-name.

How can you recover a file encrypted using EFS?
Use the domain recovery agent.

What is the Difference between Windows 2003 standard Enterprise, Premium, Data center and Web Edition?
WEB EDITION:
To position windows server 2003 more competitively against other web servers, Microsoft has released a stripped-down-yet-impressive edition of windows server 2003 designed specially for web services. the feature set and licensing allows customers easy deployment of web pages, web sites, web applications and web services.
Web Edition supports 2GB of RAM and a two-way symmetric multiprocessor(SMP). It provides unlimited anonymous web connections but only 10 inbound server message block(SMB) connections, which should be more than enough for content
publishing. The server cannot be an internet gateway, DHCP or fax server. Although you can remotely administer the server with Remote Desktop, the server can not be a terminal
server in the traditional sense. The server can belong to a domain, but cannot be a domain controller. The included version of the microsoft SQL server database Engine can support as many as 25 concurrent connections.

How do you recover an object in Active Directory, which is accidentally deleted by you, with no backup?
Using ntdsutil.exe command,we can restored the AD objects.

 What is the Logical / Physical Structures of the AD Environment?
physical structure:
Forest, Site, Domain, DC
logical structure:
Schema partition, configuration partition, domain partition and application partition

How to change the windows xp product key if wrongly installed with other product key but you have original product key? What you will do to Make your os as Genuine?
Some third party software are available for this function or reinstall this system

If 512mb Ram is there what will be the minimum and maximum Virtual memory for the system?
To workout the total virtual memory (page file) required for windows XP you should take the amount of ram in the system and + 25% (512MB + 25% (128MB) = 640MB total virtual memory. by setting both the min and max to 640MB you can increase the performances of the operating system.

What is LDAP?
LDAP, Lightweight Directory Access Protocol, is an Internet protocol that email and other programs use to look up information from a server.

What is the SYSVOL folder?
The Sysvol folder on a Windows domain controller is used to replicate file-based data among domain controllers. Because junctions are used within the Sysvol folder structure, Windows NT file system (NTFS) version 5.0 is required on domain controllers throughout a Windows distributed file system (DFS) forest.

What are application partitions? When do we use them?
Application Directory Partition is a partition space in Active Directory which an application can use to store that application specific data. This partition is then replicated only to some specific domain controllers.The application directory partition can contain any type of data except security principles (users, computers, groups).

How do we Backup Active Directory?
Backing up Active Directory is essential to maintain an Active Directory database. You can back up Active Directory by using the Graphical User Interface (GUI) and command-line tools that the Windows Server 2003 family provides.You frequently backup the system state data on domain controllers so that you can restore the most current data. By establishing a regular backup schedule, you have a better chance of recovering data when necessary.To ensure a good backup includes at least the system state data and contents of the system disk, you must be aware of the tombstone lifetime. By default, the tombstone is 60 days. Any backup older than 60 days is not a good backup. Plan to backup at least two domain controllers in each domain, one of at least one backup to enable an authoritative restore of the data when necessary.

How do we restore AD?
You can’t restore Active Directory (AD) to a domain controller (DC) while the Directory Service (DS) is running. To restore AD, perform the following steps.
Reboot the computer.
The computer will boot into a special safe mode and won’t start the DS. Be aware that during this time the machine won’t act as a DC and won’t perform functions such as authentication.
1. Start NT Backup.
2. Select the Restore tab.
3. Select the backup media, and select System State.
4. Click Start Restore.
5. Click OK in the confirmation dialog box.
After you restore the backup, reboot the computer and start in normal mode to use the restored information. The computer might hang after the restore completes; I’ve experienced a 30-minute wait on some machines.

What are GPOs?
Group Policy gives you administrative control over users and computers in your network. By using Group Policy, you can define the state of a user’s work environment once, and then rely on Windows Server 2003 to continually force the Group Policy settings that you apply across an entire organization or to specific groups of users and computers.

What domain services are necessary for you to deploy the Windows Deployment Services on your network?
Windows Deployment Services requires that a DHCP server and a DNS server be installed in the domain

What is the difference between a basic and dynamic drive in theWindowsServer2008environment?
A basic disk embraces the MS-DOS disk structure; a basic disk can be divided into partitions (simple volumes).
Dynamic disks consist of a single partition that can be divided into any number of volumes. Dynamic disks also support Windows Server 2008 RAID implementations.

What is the main purpose of a DNS server?
DNS servers are used to resolve FQDN hostnames into IP addresses and vice versa

Commonly Used DNS Records?
A-Records (Host address)
CNAME-Records (Canonical name for an alias)
MX-Records (Mail exchange)
NS-Records (Authoritative name server)
PTR-Records (domain name pointer)
SOA-Records (Start of authority)

  1. Windows 2003 vs Windows 2008

    • RODC
    • WDS instead of RIS
    • Services have been changed as roles - server manager
    • Introduction of hyper V- only on 64 bit versions
    • Enhanced event viewer
    • Bitlocker feature
    • Server core installation without GUI
    • MMC 3.0, with three pane view
    • Key management services(KMS) to activate Windows OS without connecting to Microsoft site
    • Performance enhancement using technologies like Windows SuperFetch,ReadyBoost and Readydrive
    • Windows Aero user interface
    • Instant search
    • Support for IPv6 in DNS



  1. ESX vs ESXi

    • ESXi has no service console which is a modified version of RHEL
    • ESXi is extremely thin hence results in fast installation + fast boot
    • ESXi can be purchased as an embedded hypervisor on hardware
    • ESXi has builtin server health status check


  1. ESXi 4.1 vs ESXi 5.0 - Migration

    • Local upgrade from CD
    • VMware update manager (only supports upgrade of ESX/ESXi 4.x to ESXi 5.0)


  1. ESXi 4.1 vs ESXi 5.0 - Features

    • vSphere Auto deploy
    • Storage DRS
    • HA - Primary/secondary concept changed to master/slave
    • Profile driven storage
    • VMFS version - 3 → 5
    • ESXi firewall
    • VMware hardware version - 7 →  8
    • VMware tools version - 4.1 → 5
    • vCPU - 8 → 32
    • vRAM - 256 → 1 TB
    • VMs per host - 320 → 512
    • RAM per host - 1TB → 2TB
    • USB 3.0 support
    • vApp



    • Schema Master
    • Domain naming master
    • Infrastructure master
    • PDC Emulator
    • RID master



    • GPO
    • Templates (ADMX)
    • Block inheritance
    • Enforced
    • Loopback policy


  1. Forest and Domain concepts


  1. OSI layer
  • Application Layer
  • Presentation Layer
  • Sessions Layer
  • Transport Layer
  • Network Layer
  • DataLink layer
  • Physical Layer


  1. ASA - site to site VPN


  • Uses an agent called FDM - Fault domain manager
  • HA now talks directly to hostd instead of using vcenter agent vpxa
  • Master/slave concept
  • Master
    • monitors availability of hosts/VMs
    • manages VM restarts after host failure
    • maintains list of all VMs in each host
    • restarting failed VMs
    • exchanging state with vcenter
    • monitor state of slaves
  • Slave
    • monitor running VMs and send status to master and performs restart on request from master
    • monitors master node health
    • if master fails, participates in election
  • Two different heartbeat mechanisms - Network heartbeat and datastore heartbeat
  • Network heartbeat
    • Sends between slave and master per second
    • When slave is not receiving heartbeat from master, checks whether it is isolated or master is isolated or has failed
  • Datastore heartbeat
    • To distinct between isolation and failure
    • Uses ‘Power On’ file in datastore to determine isolation
    • This mechanism is used only when master loses network connectivity with hosts
    • 2 datastores are chosen for this purpose


  • Isolation response
    • PowerOff
    • Leave Powered On
    • Shutdown
    • vMotion enables live migration of running virtual machines from one host to another with zero downtime
    • Prerequisites
      1. Host must be licensed for vMotion
      2. Configure host with at least one vMotion n/w interface (vmkernel port group)
      3. Shared storage (this has been compromised in 5.1)
      4. Same VLAN and VLAN label
      5. GigaBit ethernet network required between hosts
      6. Processor compatibility between hosts
      7. vMotion does not support migration of applications clustered using Microsoft clustering service
      8. No CD ROM attached
      9. No affinity is enabled
      10. vmware tools should be installed


  1. RAID
    • Redundant Array of Independent disks
    • A category of disk drives that uses 2 or more drives in a combination for redundancy and performance
    • Most common RAIDs: RAID 0(Striped), RAID 1(Mirroring), RAID 5


  1. Backup types
    • Backup types
      1. Full backup - Will take the backup of all selected files and reset the archive bit
      2. Copy backup - Will take the backup of all selected files but does not reset the archive bit
      3. Incremental backup - Will take the backup of files whose archive bits are set and resets it after backup
      4. Differential backup - Will take the backup of files whose archive bits are set but does not reset it after backup


  1. 2003 → 2008 migration
  • Can be done only by logging in to Windows 2003 server
  • Min of Windows 2003 SP1 required
  • Can be migrated only to same version, except for Windows server 2003 standard which can be migrated to either standard or enterprise
  • Extra space of 30 GB required prior migration
  • Cannot upgrade to server core
  • Perform forestprep and domainprep to 2008 using 2008 cd before migrating. (Copy sources/adprep folder for this)


  1. ESXi update manager


  • Global catalog (GC) is a role handled by domain controllers in an Active directory model.
  • The global catalog stores a full copy of all objects in the directory for its host domain and a partial copy of all objects for all other domains in the forest.
  • ‘Partial copy’ refers to the set of attributes that are most used for searching every object in every domain.
  • All domain controllers can be promoted as a GC.
  • GC helps in faster search of AD objects.  
  • The replicas that are replicated to the global catalog also include the access permissions for each object and attribute.
  • If you are searching for an object that you do not have permission to access, you do not see the object in the list of search results. Users can find only objects to which they are allowed access.
  • Global catalog server clients depend on DNS to provide the IP address of global catalog servers. DNS is required to advertise global catalog servers for domain controller location.
  • By default, first DC of in a forest will be a global catalog server


  1. Basic networking concepts


  1. RODC
    • New feature in Windows 2008
    • Only have the read only copy of directory database
    • RODC will have all the objects of a normal DC in read only mode. But this doesn’t include passwords. RODC does not store password of accounts.
    • Updates are replicated to RODC by writable DC
    • Password caching : A feature which enables RODC to cache password of the logged in users.
    • Password Replication Policy: Determines whether the password can be cached or not.
    • DNS can be integrated with RODC but will not directly register client updates. For any DNS change, the RODC refers the client to DNS server that hosts a primary or AD integrated zone


  1. NAS vs SAN
    • Both used as storage solution
    • NAS can be used by any device connected using LAN whereas SAN is used only by server class devices with SCSI
    • NAS is file based whereas SAN is block based storage
    • NAS is cheap while SAN is expensive
    • SAN is comparatively faster than NAS


    • Distributed Resource Scheduler
    • It is a feature of a cluster
    • DRS continuously monitors utilization across the hosts and moves virtual machines to balance the computing capacity
    • DRS uses vMotion for its functioning
    • Types of DRS
      1. Fully automated - The VMs are moved across the hosts automatically. No admin intervention required.
      2. Partially automated - The VMs are moved across the hosts automatically during the time of VM bootup. But once up, vCenter will provide DRS recommendations to admin and has to perform it manually.
      3. Manual - Admin has to act according to the DRS recommendations


    • Shared storage
    • Processor compatibility of hosts in the DRS cluster
    • vMotion prerequisites


    • Ensure vMotion is enabled on all ESX/ESXi hosts
    • Ensure that all vmware pre requisites are met
    • Verify if the ESXi/ESX host can be reconnected or if reconnecting the ESX/ESXi host resolves the issue
    • Verify that time is synchronized across environment
    • Verify that the required disk space is available


  1. What happens if a host is taken to maintenance mode
    • Hosts are taken to maintenance mode during the course of maintenance
    • In a single ESX/ESXi setup, all the VMs need to be shutdown before getting into maintenance mode
    • In a vCenter setup If DRS is enabled, the VMs will be migrated to other hosts automatically.
    • Using vmkftools
    • Copy the vmdk file and attach to a new VM
    • Using VMware converter


  1. Explain traverse folder
    • Allows or denies moving through a restricted folder to reach files and folders beneath the restricted folder in the folder hierarchy.
    • Traverse folder takes effect only when the group or user is not granted the "Bypass traverse checking user" right in the Group Policy snap-in. This permission does not automatically allow running program files.

  1. Maximum number of LUNs that can be attached to a host (ESXi 5.0)
    • 256

  1. Maximum number of vCPUs that can be assigned to a VM (ESXi 5.0)
    • 32


  1. What are the uses of ntdsutil tool?
    • Some of the main uses of ntdsutil tool
      1. Authoritative Restore - Authoritatively restores the Active Directory database or AD LDS instance
      2. ifm  - Create installation media for writable and RODC setups (Offline DC provisioning)
      3. metadata cleanup - Cleans up objects of decommissioned servers
      4. roles - Transfers and seizes operations master roles
      5. set DSRM password - Resets DSRM administrator password
      6. snapshot - Manages snapshots of the volumes that contain the Active Directory database and log files

  1. FSMO roles and its failure scenarios

  1. IPv6 addresses and its DNS record
    • 128 bit address
    • Represented as 8 groups of 4 hexadecimel digits seperated by colons
    • Represented by ‘AAAA’ record in DNS
    • Uses DHCP v6 for addressing


  1. Loadbalancer vs Clustering
    • Clustering
      1. Cluster is a group of resources that are trying to achieve a common objective, and are aware of one another.
      2. Clustering usually involves setting up the resources (servers usually) to exchange details on a particular channel (port) and keep exchanging their states, so a resource’s state is replicated at other places as well.
      3. It usually also includes load balancing, wherein, the request is routed to one of the resources in the cluster as per the load balancing policy
    • Load Balancing
      1. Used to forward requests to either one server or other, but one server does not use the other server’s resources. Also, one resource does not share its state with other resources.


    • This can be done using 2 methods
      1. Assigning
      2. Publishing
    • Assign :
      1. If you assign the program to a user, it is installed when the user logs on to the computer. When the user first runs the program, the installation is completed.
      2. If you assign the program to a computer, it is installed when the computer starts, and it is available to all users who log on to the computer. When a user first runs the program, the installation is completed.
    • Publish :
      1. You can publish a program distribution to users.
      2. When the user logs on to the computer, the published program is displayed in the Add or Remove Programs dialog box, and it can be installed from there.
    • msi packages are used for installation. Normal exe would not work.
    • Windows cannot install the software while the user is already logged on. The user need to log off and log in

  1. Group policy security filtering for users. Which all users are in there by default. Members of Authenticated Users group
    • Security filtering is a way of refining which users and computers will receive and apply the settings in a Group Policy object (GPO)
    • In order for the GPO to apply to a given user or computer, that user or computer must have both Read and Apply Group Policy (AGP) permissions on the GPO, either explicitly, or effectively through group membership
    • By default, all GPOs have Read and AGP both Allowed for the Authenticated Users group.
    • The Authenticated Users group includes both users and computers. This is how all authenticated users receive the settings of a new GPO when it is applied to an organizational unit, domain or site


  1. Relevance of host file and its location
    • Came before the concept of DNS
    • An FQDN is first checked in Host file
    • Location : C:\Windows\System32\Drivers\etc

  1. L3 switch vs Routers
    • L3 switches just have the ethernet ports only whereas the routers have WAN interfaces
    • QoS is not available with L3 switches whereas in routers it can be enabled
    • Routers have expansion slots and cards that allow them to use different media types, like serial connections for T1 and T3 circuits
    • Routers are more intelligent in handling packets
    • L3 switches does not support NAT

  1. VLAN vs Subnet
    • VLAN works at layer 2 while subnet is at layer 3
    • Subnets are more concerned about IP addresses.
    • VLANs bring more network efficiency
    • Subnets have weaker security than VLANs as all the subnet uses the same physical network

  1. Contents of System state backup
    • Registry
    • COM+ Class Registration database
    • Boot files, including the system files
    • System files that are under Windows File Protection
    • Active Directory directory service (If it is domain controller)
    • SYSVOL directory (If it is domain controller)
    • Cluster service information (If it is a part of a cluster)
    • IIS Metadirectory (If it is an IIS server)
    • Certificate Services database (If it is a certificate server)

  1. Incremental vs Differential backups
    • Incremental backup - Will take the backup of files whose archive bits are set and resets it after backup
    • Differential backup - Will take the backup of files whose archive bits are set but does not reset it after backup

  1. Robocopy
    • Microsoft tool used for copying files effectively
    • It has plenty of options to manage the copy process

  1. How do you patch microsoft applications? Frequency of patches released by Microsoft
    • The Microsoft applications can be patched using WSUS
    • In WSUS, we can create several computer groups to manage this patch process.
    • MS patches are released once in a month

    • GPO - Group Policy Object : Refers to the policy that is configured at the Active Directory level and is inherited by the domain member computers. You can configure a GPO at the site level, domain level or OU level. GPO stores policy settings in two locations GPC and GPT
    • GPO behaviour : Local Policy > Site GPO > Domain GPO > OU GPO > Child OU GPO
    • GPC - Group Policy Container :This is the AD portion of the group policy. This can be viewed using ADSI edit.  It stores version information, status information, and other policy information. When you create a new GPO, an AD object of class groupPolicyContainer gets created under the System\Policies container within your AD domain
    • GPT - Group Policy Template :  The GPT is where the GPO stores the actual settings. It stores software policy script, and deployment information.
    • GPT is stored in SYSVOL share (\\DomainNameHere\SYSVOL\Policies) whereas GPC is stored in the AD

  1. What is CPU affinity in VMware? Its impact on DRS?
    • CPU refers to a logical processor on a hyperthreaded system and refers to a core on a non-hyperthreaded system
    • By setting CPU affinity for each VM, you can restrict the assignment of VMs to a subset of available processors
    • The main use of setting CPU affinity is when there are display intensive workloads which requires additional threads with vCPUs.
    • DRS will not work with CPU affinity



  1. VMversion 4 vs VMversion 7
    • Version 4
      1. Runs on ESX 3.x
      2. Max supported RAM 64 GB
      3. Max vCPUs 4
      4. MS cluster is not supported
      5. 4 NICs/VM
      6. No USB Support
    • Version 7
      1. Runs on vSphere 4.x
      2. Max supported RAM 256 GB
      3. Max vCPUs 8
      4. MS cluster is supported
      5. 10 NICs/VM
      6. USB support

  1. What happens to the VMs if a standalone host is taken to maintenance mode?
    • In case of standalone servers , VMware recommends that VMs should be powered off before putting the server in maintenance mode
    • If we put the standalone host in maintenance mode without powering off the VMs, it will remain in the ‘entering maintenance mode’ state until the VMs are all shutdown
    • When all the VMs are powered down, the host status changes to ‘under maintenance’

  1. What is new in Windows server 2012
    • Server core improvements: no need of fresh installation, you can add/remove GUI from server manager
    • Remotely manage servers , add/remove roles etc using Server manager-manage 2008 and 2008 R2 with WMF 3.0 installation, installed by default in Server 2012
    • Remote server administration tools available for windows 8 to manage Windows server 2012 infrastructure
    • Powershell v3
    • Hyper-V 3.0
      1. supports upto 64 processors and 1 TB RAM per virtual machine
      2. upto 320 logical hardware processors and 4 TB RAM per host
      3. Shared nothing live migration, move around VMs without shared storage
  • ReFS(Resilient file system), upgraded version of NTFS- supports larger file and directory sizes. Removes the 255 character limitation on long file names and paths, the limit on the path/filename size is now 32K characters!
  • Improved CHKDSK utility that will fix disk corruptions in the background without disruption


  1. How does the backup software recognize that a file has changed since last backup?
    • The files use a bit called archive bit for tracking any change in the file.
    • The backup softwares normally checks the archive bit of the file to determine whether the file has to be backed up or not

  1. How can you edit a vm template?
    • The VM templates cannot be modified as such
    • First , the VM template have to be converted to a virtual machine
    • After making necessary machines in the virtual machine, convert the virtual machine back to template

  1. VMware configuration maximums

ESXi 5.5
ESXi 5.1
ESXi 5.0
ESXi 4.x
VMs
vCPU
64
64
32
8
RAM
1 TB
1 TB
1 TB
255 GB
vNIC
10
10
10
10
VMDK size
62 TB
1 TB
1 TB
2 TB for 8MB block
Hosts
Logical CPU
320
160
160
160
Memory
4 TB
2 TB
2 TB
1 TB
LUNs
256
256
256
256
LUN size
64 TB
64 TB
64 TB
64 TB
Virtual Machines
512
512
512
320
  1. What is the major difference between Windows server 2008 and windows server 2012 in terms of AD promotion?

           In Win 2012, dcpromo has been depreciated. In order to make a Windows server 2012 to a domain controller, the ADDS service has to be installed from the server manager. After installation, run the post-deployment configuration wizard from server manager to promote the server as AD
                 
  1. VMware hardware version comparison



  1. What is vSAN?
    • It is a hypervisor-converged storage solution built by aggregating the local storage attached to the ESXi hosts managed by a vCenter. 
  2. Recommended iSCSI configuration?
    • A separate vSwitch, and a separate network other than VMtraffic network for iSCSI traffic. Dedicated physical NICs should be connected to vSwitch configured for iSCSI traffic.
  3. What is iSCSI port binding ?
    • Port binding is used in iSCSI when multiple VMkernel ports for iSCSI reside in the same broadcast domain and IP subnet, to allow multiple paths to an iSCSI array that broadcasts a single IP address.
  4. iSCSI port binding considerations ?
    • Array Target iSCSI ports must reside in the same broadcast domain and IP subnet as the VMkernel port.
    • All VMkernel ports used for iSCSI connectivity must reside in the same broadcast domain and IP subnet.
    • All VMkernel ports used for iSCSI connectivity must reside in the same vSwitch.
    • Currently, port binding does not support network routing.
  5. Recommended iSCSI configuration of a 6 NIC infrastructure ? (Answer changes as per the infrastructure requirements)
    • 2 NICs for VM traffic
    • 2 NICs for iSCSI traffic
    • 1 NIC for vMotion
    • 1 NIC for management network
  6. Post conversion steps in P2V
    • Adjust the virtual hardware settings as required
    • Remove non present device drivers
    • Remove all unnecessary devices such as serial ports, USB controllers, floppy drives etc..
    • Install VMware tools
  7. Which esxtop metric will you use to confirm latency issue of storage ?
    • esxtop --> d --> DAVG
  8. What are standby NICs
    • These adapters will only become Active if the defined Active adapters have failed.
  9. Path selection policies in ESXi
    1. Most Recently Used (MRU)
    2. Fixed
    3. Round Robin
  10. Which networking features are recommended while using iSCSI traffic
    • iSCSI port binding
    • Jumbo Frames
  11. Ports used by vCenter
    • 80,443,902
  12. What is 'No Access' role
    • Users assigned with the 'No Access' role for an object, cannot view or change the object in any way
  13. When is a swap file created
    • When the guest OS is first installed in the VM
  14. The active directory group, where the members will be ESXi administrators by default.
    • ESX Admins
  15. Which is the command used in ESXi to manage and retrieve information from virtual machines ?
    • vmware-cmd
  16. Which is the command used in ESXi to view live performance data?
    • esxtop
  17. Command line tool used in ESXi to manage virtual disk files?
    • vmkfstools
  18. Port used for vMotion
    • 8000
  19. Log file location of VMware host
    • \var\log\vmware
  20. Can you map a single physical NIC to multiple virtual switches ?
    • No
  21. Can you map a single virtual switch to multiple physical NICs?
    • Yes. This method is called NIC teaming.
  22. VMKernel portgroup can be used for:
    • vMotion
    • Fault Tolerance Logging
    • Management traffic
  23. Major difference between ESXi 5.1 and ESXi 5.5 free versions
    • Till ESXi 5.1 free version there was a limit to the maximum physical memory to 32 GB. But from 5.5 onwards this limit has been lifted.
  24. What is IPAM server in Windows server 2012?
    •  IPAM is IP Address Management server in Windows Server 2012. It enables central management of both DHCP and DNS servers. It can also be used to discover, monitor, and audit DHCP and DNS servers.
  25. How to promote a server to domain controller in Windows server 2012?
    • DCPROMO was the conventional tool used to promote a normal server to DC. This is now deprecated in Server 2012. 
    • In Server 2012, you can convert a server into DC using the server manager console. Under Server Manager, add a new role "Active Directory Domain Services"
    • 1. What is a Hypervisor?
      It is a program that allows multiple operating systems to share a single hardware host. Each operating system appears to have the host's processor, memory, and other resources all to itself. However, the hypervisor is actually controlling the host processor and resources, allocating what is needed to each operating system in turn and making sure that the guest operating systems (called virtual machines) cannot disrupt each other.

      2. What is the hardware version used in VMware ESXi 5.5?
      Version 10

      Below is the table showing the different version of hardware used in different VMware products along with their release version
      Virtual Hardware Version
      Products
      10
      ESXi 5.5, Fusion 6.x, Workstation 10.x, Player 6.x
      9
      ESXi 5.1, Fusion 5.x, Workstation 9.x, Player 5.x
      8
      ESXi 5.0, Fusion 4.x, Workstation 8.x, Player 4.x
      7
      ESXi/ESX 4.x, Fusion 2.x/3.x Workstation 6.5.x/7.x,Player 3.x
      6
      Workstation 6.0.x
      4
      ACE 2.x, ESX 3.x, Fusion 1.x, Player 2.x
      3 and 4
      ACE 1.x, Player 1.x, Server 1.x, Workstation 5.x, Workstation 4.x
      3
      ESX 2.x, GSX Server 3.x

      3. What is the difference between the vSphere ESX and ESXi architectures?
      VMware ESX and ESXi are both bare metal hypervisor architectures that install directly on the server hardware.
      Although neither hypervisor architectures relies on an OS for resource management, the vSphere ESX architecture relied on a Linux operating system, called the Console OS (COS) or service console, to perform two management functions: executing scripts and installing third-party agents for hardware monitoring, backup or systems management.
      In the vSphere ESXi architecture, the service console has been removed. The smaller code base of vSphere ESXi represents a smaller “attack surface” and less code to patch, improving reliability and security.

      4. What is a .vmdk file?
      This isn't the file containing the raw data. Instead it is the disk descriptor file which describes the size and geometry of the virtual disk file. This file is in text format and contains the name of the –flat.vmdk file for which it is associated with and also the hard drive adapter type, drive sectors, heads and cylinders, etc. One of these files will exist for each virtual hard drive that is assigned to your virtual machine. You can tell which –flat.vmdk file it is associated with by opening the file and looking at the Extent Description field.

      Follow the below link for more details

      5. What are the different types of virtualization?
      Server Virtualization – consolidating multiple physical servers into virtual servers that run on a single physical server.

      Application Virtualization – an application runs on another host from where it is installed in a variety of ways. It could be done by application streaming, desktop virtualization or VDI, or a VM package (like VMware ACE creates with a player). Microsoft Softgrid is an example of Application virtualization.

      Presentation Virtualization – This is what Citrix Met frame (and the ICA protocol) as well as Microsoft Terminal Services (and RDP) are able to create. With presentation virtualization, an application actually runs on another host and all that you see on the client is the screen from where it is run.

      Network Virtualization – with network virtualization, the network is “carved up” and can be used for multiple purposes such as running a protocol analyzer inside an Ethernet switch. Components of a virtual network could include NICs, switches, VLANs, network storage devices, virtual network containers, and network media.

      Storage Virtualization – with storage virtualization, the disk/data storage for your data is consolidated to and managed by a virtual storage system. The servers connected to the storage system aren’t aware of where the data really is. Storage virtualization is sometimes described as “abstracting the logical storage from the physical storage.

      6. What is VMware vMotion and what are its requirements?
      VMware VMotion enables the live migration of running virtual machines from one physical server to another with zero downtime.

      VMotion lets you:
      • Automatically optimize and allocate entire pools of resources for maximum hardware utilization and
      • availability.
      • Perform hardware maintenance without any scheduled downtime.
      • Proactively migrate virtual machines away from failing or under performing servers.
      Below are the pre-requisites for configuring vMotion
      • Each host must be correctly licensed for vMotion
      • Each host must meet shared storage requirements
        • vMotion migrates the vm from one host to another which is only possible with both the host are sharing a common storage or to any storage accessible by both the source and target hosts. 
        • A shared storage can be on a Fibre Channel storage area network (SAN), or can be implemented using iSCSI SAN and NAS.
        • If you use vMotion to migrate virtual machines with raw device mapping (RDM) files, make sure to maintain consistent LUN IDs for RDMs across all participating hosts.
      • Each host must meet the networking requirements
        • Configure a VMkernel port on each host.
        • Dedicate at least one GigE adapter for vMotion.
        • Use at least one 10 GigE adapter if you migrate workloads that have many memory operations.
        • Use jumbo frames for best vMotion performance.
        • Ensure that jumbo frames are enabled on all network devices that are on the vMotion path including physical NICs, physical switches and virtual switches.

      7. What is the difference between clone and template in VMware?
      Clone
      • A clone is a copy of virtual machine.
      • You cannot convert back the cloned Virtual Machine.
      • A Clone of a Virtual Machine can be created when the Virtual Machine is powered on
      • Cloning can be done in two ways namely Full Clone and Linked Clone.
      • A full clone is an independent copy of a virtual machine that shares nothing with the parent virtual machine after the cloning operation. Ongoing operation of a full clone is entirely separate from the parent virtual machine.
      • A linked clone is a copy of a virtual machine that shares virtual disks with the parent virtual machine in an ongoing manner. This conserves disk space, and allows multiple virtual machines to use the same software installation.
      • Cloning a virtual machine can save time if you are deploying many similar virtual machines. You can create, configure, and install software on a single virtual machine, and then clone it multiple times, rather than creating and configuring each virtual machine individually.

      Template
      • A template is a master copy or a baseline image of a virtual machine that can be used to create many clones.
      • Templates cannot be powered on or edited, and are more difficult to alter than ordinary virtual machine.
      • You can convert the template back to Virtual Machine to update the base template with the latest released patches and updates and to install or upgrade any software and again convert back to template to be used for future deployment of Virtual Machines with the latest patches.
      • Convert virtual Machine to template cannot be performed, when Virtual machine is powered on.  Only Clone to Template can be performed when the Virtual Machine is powered on.
      • A template offers a more secure way of preserving a virtual machine configuration that you want to deploy many times.
      • When you clone a virtual machine or deploy a virtual machine from a template, the resulting cloned virtual machine is independent of the original virtual machine or template.

      8. What is promiscuous mode in Vmware?
      • Promiscuous mode is a security policy which can be defined at the virtual switch or portgroup level
      • A virtual machine, Service Console or VMkernel network interface in a portgroup which allows use of promiscuous mode can see all network traffic traversing the virtual switch.
      • If this mode is set to reject, the packets are sent to intended port so that the intended virtual machine will only be able to see the communication.
      • Example: In case you are using a virtual xp inside any Windows VM. If promiscuous mode is set to reject then the virtual xp won't be able to connect the network unless promiscuous mode is enabled for the Windows VM.

      9. What is the difference between Thick provision Lazy Zeroed, Thick provision Eager Zeroed and Thin provision?
      Thick Provision Lazy Zeroed
      • Creates a virtual disk in a default thick format.
      • Space required for the virtual disk is allocated when the virtual disk is created.
      • Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.
      • Using the default flat virtual disk format does not zero out or eliminate the possibility of recovering deleted files or restoring old data that might be present on this allocated space.
      • You cannot convert a flat disk to a thin disk.

      Thick Provision Eager Zeroed
      • A type of thick virtual disk that supports clustering features such as Fault Tolerance.
      • Space required for the virtual disk is allocated at creation time.
      • In contrast to the flat format, the data remaining on the physical device is zeroed out when the virtual disk is created.
      • It might take much longer to create disks in this format than to create other types of disks.

      Thin Provision
      • It provides on on-demand allocation of blocks of data.
      • All the space allocated at the time of creation of virtual disk is not utilized on the hard disk, rather only the size with utilized data is locked and the size increases as the amount of data is increased on the disk.
      • With thin provisioning, storage capacity utilization efficiency can be automatically driven up towards 100% with very little administrative overhead.

      10. What is a snapshot?
      A snapshot is a “point in time image” of a virtual guest operating system (VM). That snapshot contains an image of the VMs disk, RAM, and devices at the time the snapshot was taken. With the snapshot, you can return the VM to that point in time, whenever you choose. You can take snapshots of your VMs, no matter what guest OS you have and the snapshot functionality can be used for features like performing image level backups of the VMs without ever shutting them down.

      11. What is VDI?
      • VDI stands for Virtual Desktop Infrastructure where end user physical machine like desktop or laptop are virtualized due to which VMware described VDI as "delivering desktops from the data center”.
      • Once VDI is used the end user connect to their desktop using a device called thin client.
      • The end user can also connect to their desktop using VMware Horizon View installed on any desktop or mobile devices

      12. What is VMware HA?
      • VMware HA i.e. High Availability which works on the host level and is configured on the Cluster.
      • A Cluster configured with HA will migrate and restart all the vms running under any of the host in case of any host-level failure automatically to another host under the same cluster.
      • VMware HA continuously monitors all ESX Server hosts in a cluster and detects failures.
      • VMware HA agent placed on each host maintains a heartbeat with the other hosts in the cluster using the service console network. Each server sends heartbeats to the others servers in the cluster at five-second intervals. If any servers lose heartbeat over three consecutive heartbeat intervals, VMware HA initiates the failover action of restarting all affected virtual machines on other hosts.
      • You can set virtual machine restart priority in case of any host failure depending upon the critical nature of the vm.
      NOTE: Using HA in case of any host failure with RESTART the vms on different host so the vms state will be interrupted and it is not a live migration

      13. What is the difference between VMware HA and vMotion?
      VMware HA is used in the event when any of the hosts inside a cluster fails then all the virtual machines running under it are restarted on different host in the same cluster.
      Now HA is completely dependent on vMotion to migrate the vms to different host so vMotion is just used for the migration purpose between multiple hosts. vMotion also has the capability to migrate any vm without interrupting its state to any of the host inside cluster.

      14. What is storage vMotion?
      • Storage vMotion is similar to vMotion in the sense that "something" related to the VM is moved and there is no downtime to the VM guest and end users. However, with SVMotion the VM Guest stays on the server that it resides on but the virtual disk for that VM is what moves.
      • With Storage vMotion, you can migrate a virtual machine and its disk files from one datastore to another while the virtual machine is running.
      • You can choose to place the virtual machine and all its disks in a single location, or select separate locations for the virtual machine configuration file and each virtual disk.
      • During a migration with Storage vMotion, you can transform virtual disks from Thick-Provisioned Lazy Zeroed or Thick-Provisioned Eager Zeroed to Thin-Provisioned or the reverse.
      • Perform live migration of virtual machine disk files across any Fibre Channel, iSCSI, FCoE and NFS storage

      15. What is VMware DRS and how does it works?
      • Here DRS stands for Distributed Resource Scheduler which dynamically balances resource across various host under Cluster or resource pool.
      • VMware DRS allows users to define the rules and policies that decide how virtual machines share resources and how these resources are prioritized among multiple virtual machines.
      • Resources are allocated to the virtual machine by either migrating it to another server with more available resources or by making more “space” for it on the same server by migrating other virtual machines to different servers.
      • The live migration of virtual machines to different physical servers is executed completely transparent to end-users through VMware VMotion
      • VMware DRS can be configured to operate in either automatic or manual mode. In automatic mode, VMware DRS determines the best possible distribution of virtual machines among different physical servers and automatically migrates virtual machines to the most appropriate physical servers. In manual mode, VMware DRS provides a recommendation for optimal placement of virtual machines, and leaves it to the system administrator to decide whether to make the change.

      16. What is VMware Fault Tolerance?
      • VMware Fault Tolerance provides continuous availability to applications running in a virtual machine, preventing downtime and data loss in the event of server failures.
      • VMware Fault Tolerance, when enabled for a virtual machine, creates a live shadow instance of the primary, running on another physical server.
      • The two instances are kept in virtual lockstep with each other using VMware vLockstep technology
      • The two virtual machines play the exact same set of events, because they get the exact same set of inputs at any given time.
      • The two virtual machines constantly heartbeat against each other and if either virtual machine instance loses the heartbeat, the other takes over immediately. The heartbeats are very frequent, with millisecond intervals, making the failover instantaneous with no loss of data or state.
      • VMware Fault Tolerance requires a dedicated network connection, separate from the VMware VMotion network, between the two physical servers.

      17. In a cluster with more than 3 hosts, can you tell Fault Tolerance where to put the Fault Tolerance virtual machine or does it chose on its own?
      You can place the original (or Primary virtual machine). You have full control with DRS or vMotion to assign it to any node. The placement of the Secondary, when created, is automatic based on the available hosts. But when the Secondary is created and placed, you can vMotion it to the preferred host.

      18. How many virtual CPUs can I use on a Fault Tolerant virtual machine ?
      vCenter Server 4.x and vCenter Server 5.x support 1 virtual CPU per protected virtual machine.

      19. What happens if vCenter Server is offline when a failover event occurs?
      When Fault Tolerance is configured for a virtual machine, vCenter Server need not be online for FT to work. Even if vCenter Server is offline, failover still occurs from the Primary to the Secondary virtual machine. Additionally, the spawning of a new Secondary virtual machine also occurs without vCenter Server.

      20. What is the difference between Type 1 and Type 2 Hypervisor?
      Type 1 Hypervisor
      • This is also known as Bare Metal or Embedded or Native Hypervisor.
      • It works directly on the hardware of the host and can monitor operating systems that run above the hypervisor.
      • It is completely independent from the Operating System.
      • The hypervisor is small as its main task is sharing and managing hardware resources between different operating systems.
      • A major advantage is that any problems in one virtual machine or guest operating system do not affect the other guest operating systems running on the hypervisor.
      • Examples: VMware ESXi Server, Microsoft Hyper-V, Citrix/Xen Server

      Type 2 Hypervisor
      • This is also known as Hosted Hypervisor.
      • In this case, the hypervisor is installed on an operating system and then supports other operating systems above it.
      • It is completely dependent on host Operating System for its operations
      • While having a base operating system allows better specification of policies, any problems in the base operating system a ffects the entire system as well even if the hypervisor running above the base OS is secure.
      • Examples: VMware Workstation, Microsoft Virtual PC, Oracle Virtual Box
      21. How does vSphere HA works?
      When we configure multiple hosts for HA cluster, a single host is automatically elected as the master host. The master host communicates with vCenter Server and monitors the state of all protected virtual machines and of the slave hosts. When you add a host to a vSphere HA cluster, an agent is uploaded to the host and configured to communicate with other agents in the cluster.

      22. What are the monitoring methods used for vSphere HA?
      The Master and Slave hosts uses two types of monitoring the status of the hosts
      • Datastore Heartbeat
      • Network Heartbeat

      23. What are the roles of master host in vSphere HA?
      • Monitoring the state of slave hosts. If a slave host fails or becomes unreachable, the master host identifies which virtual machines need to be restarted.
      • Monitoring the power state of all protected virtual machines. If one virtual machine fails, the master host ensures that it is restarted. Using a local placement engine, the master host also determines where the restart should be done.
      • Managing the lists of cluster hosts and protected virtual machines.
      • Acting as vCenter Server management interface to the cluster and reporting the cluster health state.
      24. How is a Master host elected in vSphere HA environment?
      When vSphere HA is enabled for a cluster, all active hosts (those not in standby or maintenance mode, or not disconnected) participate in an election to choose the cluster's master host. The host that mounts the greatest number of datastores has an advantage in the election. Only one master host typically exists per cluster and all other hosts are slave hosts.

      If the master host fails, is shut down or put in standby mode, or is removed from the cluster a new election is held.

      25. If the vCenterserver goes down with a situation that it was pre configured with vSphere HA and DRS, so after power down will HA and DRS perform their task?
      vSphere HA is not dependent on vCenterserver for its operations as when HA is configured it installs an agent into each host which does its part and is not dependent on vCenterserver. Also HA doesnot uses vMotion, it justs restarts the vms into another host in any case of host failure.

      Further vSphere DRS is very much dependent on vCenterserver as it uses vMotion for its action for live migration of vms between multiple hosts so in case vCenterserver goes down the vMotion won't work leading to failure of DRS.