VMWare Interview Questions

Q.What is Service Console? The service console is developed based up on Redhat Linux Operating system, it is used to manage the VMKernel Q.What happens when you take a snapshot of virtual machine? Answer: When you take a snapshot of virtual machine, it makes a copy of the .vmdk file and its memory, saves them along with the other virtual machine files. "vmware-cmd createsnapshot " each snapshot occupies the same size of .vmdk file in the datastore. So if you take more snapshots, more space will be utilized. Q.Are we able to add odd number virtual CPUs to our virtual machines, for example 3 or 5 VCPU as compared to VI3 version when virtual SMP only supports 2 or 4 VCPU per virtual machine ? Answer: Yes, we can now add odd number VCPU to our virtual machines. Q.What is the limitation for configuring VMware Fault Tolerance for a virtual machine ? Answer: Virtual machine selected for VMware FT must be provisioned with thick disk and not thin disk, if it was provisioned with thin disk, there will be a prompt to inflate the existing disk size. Q.What is the disadvantage of configuring VM direct path I/O for a virtual machine ? Answer: With a distributed virtual switch, the network statistics and policies of the virtual machine that has been vmotion to another ESX Server will migrate with the VM. This provides the ability for network vmotion and is useful for implementing inline intrusion detection systems and firewalls. Q.Does ESX 4 and ESXi 4 support jumbo frames and TSO ? Answer: Yes, both ESX 4 and ESXi 4 provides support for jumbo frames as well as TSO, these can now be configured in the GUI as compared to VI3 where administrators could only do it via command lines. Q.What is the different between VMware Data Protection as compared to the traditional VMware Consolidated Backup ? Answer: VMware Data Protection supports all storage architecture for backup and restore via LAN and SAN. It also supports full, incremental and differential file level backup options.

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Q.What is the key driving factor for users adopting VMware vCenter Data Recovery ? Answer: It's an API that runs in a virtual machine within your vCenter, it provides agentless backup and can backup virtual machines even when they are being vmotion to a different host. Q.Can we perform Storage Vmotion now via the GUI inside vCenter ? Answer: Yes, Storage Vmotion feature is now avaliable in the vSphere Client connected to vCenter Server. It provides full support for FC SAN and NFS. Q.When using vCenter Linked Mode feature, what are the functions that could be shared among the vCenters in this link ? Answer: vCenter Linked Mode allows administrator to centrally manage all the vCenter within a single view, roles and licenses can be shared across the vCenters configured in a link. Q.Do I still require a Flexnet License Server if all my ESX Servers are ESX 4 and ESXi 4 ? Answer: No, you no longer require a license server for the to manage the new ESX Servers. All licenses are managed within the vCenter Server. Q.If my customer has a hybrid environment where they still have ESX 3 and ESX 3.5, can vCenter communicate with the existing Flexnet License Server ? Answer: Yes, vCenter can communicate with existing license servers so as to allow it to manage legacy ESX Servers. vCenter will pull the licenses for legacy hosts from the flexnet license server. Q.Why am I unable to hot add CPU and memory to virtual machine ? Answer: You are required to enable this function under the virtual machine settings in order to use it. Therefore, it is advisable to enable it before you start your virtual machine for the very first time. Q.What are the basic commands to troubleshoot  connectivity between vSphere Client /vCenter to ESX server? Answer: VMWare Kernel is a Proprietary kernel  of vmwareand is not based on any of the flavors of Linux operating systems, .VMkernel requires an operating system to boot and manage the kernel. A service console is being provided when VMWare kernel is booted. Only service console is based up on Red hat Linux OS not VMkernel.

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Q.What is the use of Service Console port ? Answer: Service console port group required to manage the ESX server and it acts as the management network for the ESX.Vcenter/Vsphere Client uses the service console IP's to communicate with the ESX server. Q.What is the use of VMKernel Port ? Answer: Vmkernel port is used by ESX/ESXi for vmotion, ISCSI & NFS communications. ESXi uses Vmkernel as the management network  since it don't have service console built with it. Q.What is the use of Virtual Machine Port Group? Answer: Virtual Machine port group is used by Virtual machine communication. Q.How Virtual Machine communicates to another servers in Network ? Answer: All the Virtual Machines which are configured in VM Port Group are able to connect to the other machines on the network. So this port group enables communication between vSwitch and Physical Switch by the use of uplink (Physical NIC) associated with the port group. Q.What are the different types of Partitions in ESX server? Answer:  / -root Swap /var /Var/core /opt /home /tmp Q.What is the default number of ports configured with the Virtual Switch? Answer: When the time of Virtual switch created, Vswitch is created with 56 ports by default. We can extend the no of ports by editing the vswitch properties. Q.Is it true we can now use the new VMware Update Manager to upgrade our legacy ESX Servers (For example: ESX 3.5) to ESX 4.0 version ? Answer: Yes, the new VUM has the ability to upgrade your legacy ESX Server hosts for you. However, if you are upgrading a standalone host, you will be required to power off all virtual machines running on that host. Q.How come we are unable to use our existing VI Client to manage our ESX 4 and vCenter 4 ? Answer: No, the legacy VI Client is unable to manage newer ESX Server Hosts and vCenter. You will need to install vSphere Client to manage newer ESX Server Hosts and vCenter as well as legacy ESX Hosts. Q.In vSphere, can we configure bidirectional CHAP authentication for iSCSI ? Answer: Yes, we can now configure bidirectional CHAP authenticaton for iSCSI software. It is fully supported. Previously, we could only configure unidirectional CHAP authentication. Q.Do we still need to configure a Service Console port for iSCSI initiator ? Answer: No, we no longer need a Service Console for software iSCSI initator. The vmkiscsid no longer runs in the Service Console. There have been improvements made to the new iSCSI stack in the kernel and also with the use of TCP/IP2 which has multi threading capabilities. Q.What is the maximum number of CPU and maximum amount of memory a virtual machine can scale ? Answer: In vSphere, a virtual machine can now be configure with a maximum of 8 virtual CPUs and 255 GB of memory. Q.What is the maximum amount of logical CPUs and memory per ESX Server 4 host can scale ? Answer: ESX Server 4 now supports a maximum of 64 logical CPUs and 1 TB of memory.

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Q.What actions allow us to configure thin disk provisioning for a virtual machine ? Answer: When we create a new virtual machine, clone an existing virtual machine, clone a template or perform Storage Vmotion on an existing virtual machine. Q.What is the benefit of configuring thin disk provisioning as compared to thick disk provisioning for a virtual machine ? Answer: When we configure thin disk provisioning the virtual machine only uses the space that it requires and not the entire disk size, this allows the remaining unused space for other virtual machines. This enables us to do Storage Over-commitment and use the storage more efficiently. Q.Will my virtual machines still have connection if the virtual center that stores my Distributed vSwitch configuration goes down ? Answer: Yes, this is because the Distributed vSwitch has an control plane which sits at the vCenter Server level and an I/O plane which are the form of hidden vSwitches sitting at the ESX level. Therefore, even if the vCenter goes down, virtual machines continue to have connectivity through the I/O plane at the ESX level. Q.What is the maximum number of ESX Hosts we can connect to a single distributed switch ? Answer: We can connect up to 64 ESX hosts per distributed switch and vCenter 4 can support up a maximum of 16 distributed switches. Which means we can have up to 1024 hosts on these 16 distributed switches. Q.What is the version of the 64 bit Service Console running in ESX 4 ? Answer: The Service Console is a 2.6 linux kernel compatible with Red Hat Enterprise Linux 5.2 or CentOS 5.2 version. Q.What is the maximum number of uplinks or ports per ESX 4 or ESXi 4 Host ? Answer: The maximum number of uplinks per ESX 4 or ESXi 4 Host is 32 uplinks. Q.Can we install vCenter Server on a 64 bit Windows OS ? Answer: Yes, vCenter Server can be installed on both 32-bit and 64-bit Windows OS. Q.Does ESX/ESXi 4 supports round robin multipathing policy ? Answer: Yes besides fixed (preferred) and most recently used (MRU), ESX/ESXi 4 now supports round robin multipathing policy and it has to be configured on the storage level. Q.Can vCenter 4 support a cluster which includes ESX 3.x and ESX 4 hosts ? Answer: Yes, we can cluster legacy ESX 3.x hosts and ESX 4 hosts together in the same cluster. vCenter will have to connect to the flexnet license server to manage the licenses for the legacy hosts. However, new features such as hot add and PCI pass through may not be avaliable to the VMs on legacy hosts. Q.When upgrading from virtual center 2.x to vCenter 4, is there downtime for the host and do we need to re add the ESX hosts back into the inventory ? Answer: No, there's no time for the hosts and existing hosts will remain in the inventory. However, there will be downtime for virtual center. Remember to backup the databases as during the upgrade process, the database schemas are changed and in the event of a upgrade failure, you will not be able to roll back and you will have to do a restore. Q.When we hot add memory to a powered on VM, will the swap file get dynamically increased ? Answer: When we hot add memory to a powered on VM, the swap file size will get dynamically increase. Q.When we hot add memory to a powered on VM and the swap file get dynamically increased, what happens if there is not enough disk space to meet the growing vswap file size ? Answer: You will not be able to add memory to that VM that has not enough memory for the swap file to grow and you will receive an error. Q.Can we add USB controllers to our VM in ESX/ESXi 4 ? Answer: Yes, we now have the ability to hot plug USB controller into our VMs while they are running. However, the usb device has to be connected to the ESX Server and not the client local machine. Q.When installing convertor plug-in, I get a 404 error and the installation halts ? Answer: During installation of vCenter Convertor you will have to enter the FQDN instead of the IP address or netbios name as this may cause you to receive the 404 error when installing the vCenter convertor plug-in later.

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Q.Where is Distributed Power Management configured and what are the protocols it uses ? Answer: DPM is configured and managed at the DRS cluster level. It uses IPMI, ILO and Wake On LAN protocols. DRS can use DPM to put under utilized hosts into standby modes to save power consumption. Q.What is new with vCenter 4 user access and role management as compared to the virtual center 2.5 Answer: vCenter 4 allows us the ability to assign administrators to inventory objects such as networks and datastores which were not available with the previous virtual center version. Q.What are the new tasks we can schedule in vCenter 4 task scheduler ? Answer: vCenter 4 task scheduler allows us the ability to schedule a task to increase the resources in a resource pool or virtual machine. This would be good to cater to the needs of virtual machines that will require additional ad-hoc resources such as finance department doing month end closing which may result in resources surge on their machines. Q.How does VMware HA on an ESXi Server sends out heart beat if ESXi does not have a service console ? Answer: VMware HA clusters configured for ESXi Servers uses the vmkernel present on all ESXi Servers to send and receive heart beats. Whereas, on ESX Servers the heartbeat is send and receive through the service console. Therefore, we may not want to cluster ESX and ESXi Servers together in the same cluster. Q.Can we create a cluster with ESX and ESXi Servers ? Answer: Yes. However, VMware HA may not work as both servers uses different port groups to send out heart beats. Vmotion and DRS may still work. This is not a supported practise. Q.What is the limitation for configuring VMware Fault Tolerance for a virtual machine ? Answer: Virtual machine selected for VMware FT must be provisioned with thick disk and not thin disk, if it was provisioned with thin disk, there will be a prompt to inflate the existing disk size. Q.How can I grow an existing VMFS LUN without creating an extent or physical partition ? Answer: We can use the grow function to grow an existing VMFS LUN. If the LUN is out of space, first we must get the storage administrator to grow the same LUN on the storage level with storage array management utilities then within the vCenter Server, we can then select the LUN and grow it. Q.How come the hot add CPU and hot add memory option is greyed out for my VM ? Answer: This feature is currently available only on supported guest OS such as Windows Server 2003 enterprise and Windows 2008 datacenter edition. The type of license also plays a part on the availability of this feature to the VM. Q.What does the channel number stands for in vmhba#:T:C:L? Answer: The only real example that I've seen in vSphere so far, is the software iSCSI initiator. If you give the VMkernel multiple VMkernel ports, and each port can reach (over its own subnet) different targets, they are listed with different "channel" numbers, to indicate whether they use the first VMkernel port, the second or the third. Q.Can we install VMware Consolidated Backup VCB in a virtual machine ? Answer: Yes, VCB can now be installed in a VM and it can be use to backup VMs running on iSCSI and NFS. However, if you wish to backup VMs whose files reside on an FC San LUN, VCB must be installed on a physical machine. Q.Does VMware View 3 work with VMware vSphere 4 ? Answer: No, currently VMware View 3 is only supported on VI 3.5 infrastructure and it is not supported to work with vSphere 4 environment. Q.Is the Service Console root file system still running on ext3 file system ? Answer: No, the SC root file system is now running on VMDK and this is automatically created during initial installation of ESX Servers. Q.Is it possible to configure VMware Update Manager 4 to point to WSUS to grab windows updates ? Answer: No, this is not possible as the VUM Server is unable to communicate with the WSUS Server.

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Q.Can vCenter 4 perform Storage Vmotion on a legacy ESX 3.x Host and convert the VM virtual disk from thick to thin disk ? Answer: Yes, vCenter 4 is able to convert a VM's virtual disk from thick to thin using storage vmotion. Q.I understand that Oracle databases licensed by per CPU, how does that translate to the number of license I have to purchase if I port it over to VM ? Answer: In order for you to run your Oracle DB within a VM on that ESX Server, you have to purchase license for each physical CPU on that ESX Server box. Q.How come there is no standalone boot CD for VMware Convertor 4.0 for me to download for use for cold cloning ? Answer: VMware vCenter Converter Standalone 4.0.1 does not support cold cloning, you must use an earlier Converter edition boot CD 3.0.x Enterprise Edition. Q.When we convert a VM from thin disk to thick disk, which state must the VM be in to perform the request ? Answer: The VM must be in the powered off state in order to be converted from thin to thick disk. Q.What is the default multipathing policy for ESX 4 ? Answer: The hypervisor determines whether to use MRU or Fixed based on the type of arrays it detects. If array is active\passive, it would be treated as MRU. If array is active\active, it would be treated as fixed Q.What is the difference between Enhanced vmxnet and vmxnet3 ? Answer: Vmxnet3 is an improved version of enhanced vmxnet, some benefits and improvements are MSI/MSI-X support, Side Scaling, checksum and TCP Segmentation Offloading (TSO) over IPv6, off-loading and Large TX/RX ring sizes. Q.When we replicate the LUNs over resignaturing only occurs for VMFS LUNs and not RDM, how do we get the replicated RDM to work ? Answer: You can replicate the RDM to a new array, but the mapping file that is configured on the vm itself will no longer be pointing to the same location it was previously, so the RDM has to be re-mapped to the VM in a DR scenario. Q.After installing plug-in inside the VC, I am unable to enable the plug-in and it always shows as disabled. Answer: Go to services.msc ensure that the Virtual Center Management Webservices is running and then relogin the vSphere Client and enable the plug-in. Q.What is the difference between ephemeral and dynamic binding on a distributed virtual switch ? Answer: Ephemeral a new port on every power-on. The port is destroyed when the VM disconnects from the port. Dynamic assign a port when the VM is powered on, it uses a concept similar to DHCP in that if the same port is available then it will renew that one. Q.What is the difference between a thick virtual disk and eager zeroed thick virtual disk ? Answer: Thick virtual disk does not format the VMDK at the time of deployment. This means that data, which needs to be written, must pause while the blocks required to store the data are zeroed out. An eager zeroed thick virtual disk actually formats all of its data blocks at the time of deployment. Q.What kind of permissions do we need to provide when configuring a NAS Server ? Answer: We need to configure permission for the administrator group account rights on the NAS Server so that the ESX Server can access the NAS Server. Q.Storage View tabs in the SAN storage datastore is blank and does not show anything ? Answer: Start the vCenter Mount Service and virtual disk service, then restart the vCenter Server service on the Windows OS. Then click on refresh for the storage view tabs. Q.Can we migrate VMs running on ESX host with VMware Hardware Version 7 to ESX host with VMware Hardware Version 4 ? Answer: No we cannot migrate VMs running on hardware version 7 back to hardware version 4. VMware hardware version 7 only exists on ESX4 and greater. However, it is possible to migrate VMs running on ESX host with hardware version 4 to ESX host running on hardware version 7. Q.Does VMware have an online page where we can search for all the technical white papers ? Yes. Q.Does VCB supports Windows Server 2008 ? Answer: VCB version 1.5 supports Windows Server 2008. Q.What are the security options available for ESX vswitch? Answer: Promiscuous Mode - Reject MAC Address changes - Accept Forged Transmits – Accept Q.What is Promiscuous Mode ? Answer: 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. It can be useful when you are running virtual machines with network sniffers to capture packet in that network. Q.What is MAC Address changes? Answer: All the virtual machines nics are provide with the MAC address at the time of creation and it is stored in .VMX file. If the packet  doesn't match with the MAC address as same as in the .VMX  file , it does not allow incoming traffic to the VM by setting this option as reject. If it is set as Accept,ESX accepts requests to change the effective MAC address to other than the MAC address save din the .VMX file. Q.What is Forged Transmits ? Answer: Which is same as the Mac Address changes setting but it worked for the outgoing traffic but the MAC address changes setting is for incoming traffic. Q.What is VST , EST & VGT? Answer: Please refer my blog post on VST , EST & VGT . Q.What are the Traffic Shaping policies available in the Vswitch? Answer: Traffic shaping policies are disabled by default. There are 3 different traffic shaping policy setting Average Bandwidth Peak Bandwidth Burst Size Average Bandwidth is defined in KBPS Peak bandwidth is defined in KBPS Burst Size is defined in Kilobytes Q.What are the Load balancing policies available in vswitch? Answer: Route based on the originating virtual switch port ID Route based on source MAC hash Route based on IP hash Route based on the originating virtual switch port ID - Chooses an uplink based on the virtual port where the traffic entered the virtual switch.  The traffic will be always send with that same uplink until that particular uplink is failed and failed over to another NIC. Route based on source MAC hash - Choose an uplink based on a hash of the source Ethernet MAC address.The traffic will be always send with that same uplink until that particular uplink is failed and failed over to another NIC. Route based on IP hash - Choose an uplink based on a hash of the source and destination IP addresses of each packet. Q.What are the  types for Network Failover Detection settings? Answer: Link Status only Beacon Probing Link Status only - Relies solely on the link status provided by the network adapter. This detects failures, such as cable pulls and physical switch power failures, but it cannot detect configuration errors, such as a physical switch port being blocked by spanning tree or misconfigured to the wrong VLAN or cable pulls on the other side of a physical switch. Beacon Probing -  Sends out and listens for beacon probes — Ethernet broadcast frames sent by physical adapters to detect upstream network connection failures — on all physical Ethernet adapters in the team. In addition to link status, to determine link failure. This detects many of the failures which are not detected by Link Status.

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Q.What is the command to  check the IP address along with the detailed network cards assigned to the esx server? Ifconfig -a Output appears like this lo        Link encap:Local Loopback inet addr:127.0.0.1  Mask:255.0.0.0 UP LOOPBACK RUNNING  MTU:16436  Metric:1 RX packets:9365 errors:0 dropped:0 overruns:0 frame:0 TX packets:9365 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:8127714 (7.7 MiB)  TX bytes:8127714 (7.7 MiB) vmnic0    Link encap:Ethernet  HWaddr 00:0C:29:85:0D:76 UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:100772 errors:0 dropped:0 overruns:0 frame:0 TX packets:5103 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:35475848 (33.8 MiB)  TX bytes:402120 (392.6 KiB) Interrupt:145 vmnic1    Link encap:Ethernet  HWaddr 00:0C:29:85:0D:80 UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:105895 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:35894203 (34.2 MiB)  TX bytes:0 (0.0 b) Interrupt:129 vmnic2    Link encap:Ethernet  HWaddr 00:0C:29:85:0D:8A UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:105908 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:35895750 (34.2 MiB)  TX bytes:0 (0.0 b) Interrupt:137 vmnic3    Link encap:Ethernet  HWaddr 00:0C:29:85:0D:94 UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:105690 errors:0 dropped:0 overruns:0 frame:0 TX packets:228 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:35883279 (34.2 MiB)  TX bytes:13680 (13.3 KiB) Interrupt:145 vswif0    Link encap:Ethernet  HWaddr 00:50:56:4D:69:D1 inet addr:192.168.0.75  Bcast:192.168.0.255  Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:14893 errors:0 dropped:0 overruns:0 frame:0 TX packets:2575 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:966513 (943.8 KiB)  TX bytes:230028 (224.6 KiB) vswif1    Link encap:Ethernet  HWaddr 00:50:56:4F:45:B1 BROADCAST MULTICAST  MTU:1500  Metric:1 RX packets:11042 errors:0 dropped:0 overruns:0 frame:0 TX packets:30 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:717158 (700.3 KiB)  TX bytes:1260 (1.2 KiB) ========================================================================= You can use "ip addr" command also to view the ip information ========================================================================= # ip addr 1: lo: mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo 2: vmnic0: mtu 1500 qdisc noop qlen 1000 link/ether 00:0c:29:85:0d:76 brd ff:ff:ff:ff:ff:ff 3: vmnic1: mtu 1500 qdisc noop qlen 1000 link/ether 00:0c:29:85:0d:80 brd ff:ff:ff:ff:ff:ff 4: vmnic2: mtu 1500 qdisc noop qlen 1000 link/ether 00:0c:29:85:0d:8a brd ff:ff:ff:ff:ff:ff 5: vmnic3: mtu 1500 qdisc noop qlen 1000 link/ether 00:0c:29:85:0d:94 brd ff:ff:ff:ff:ff:ff 6: vswif0: mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:50:56:4d:69:d1 brd ff:ff:ff:ff:ff:ff inet 192.168.0.75/24 brd 192.168.0.255 scope global vswif0 7: vswif1: mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:50:56:4f:45:b1 brd ff:ff:ff:ff:ff:ff 9: vswif2: mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:50:56:43:92:be brd ff:ff:ff:ff:ff:ff inet 192.168.0.96/24 brd 192.168.0.255 scope global vswif2 ========================================================================= Q.What is the command to check the ESX vswitch details, port group and its ip address? Answer: Esxcfg-vswitch -l Outuput will appear like this: ========================================================================= # esxcfg-vswitch -l Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks vSwitch0       32          4           32                1500    vmnic0 PortGroup Name      VLAN ID  Used Ports  Uplinks Service Console     0        1           vmnic0 VMkernel            0        1           vmnic0 Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks vSwitch1       64          3           64                1500    vmnic2,vmnic1 PortGroup Name      VLAN ID  Used Ports  Uplinks VM-10.0.0 subnet    0        0           vmnic2,vmnic1 VM-192.168.0 subnet 0        0           vmnic2,vmnic1 Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks vSwitch2       64          4           64                1500    vmnic3 PortGroup Name      VLAN ID       Used Ports             Uplinks Service Console 2     0                      1                           vmnic3 Vmotion             0        1                                              vmnic3 ========================================================================= From the above output, we come to know that we have 3 virtual switches named vSwitch0,vSwitch1 and vSwitch2. 4 uplinks (physical nics in our esx server) Vmnic0,vmnic1,vmnic2,vmnic3. vswitch0 constains 2 port group (Service Console & VMKernel), vSwitch1 contains 2 virtual machine port group (VM-10.0.0 subnet & VM-192.168.0 subnet) and Vswitch2 contains 2 port group (Service Console 2 & Vmotion) port group. Q.What is command to get the information about Service console ports and its IP address assigned to it? Answer: esxcfg-vswif -l Output will appear like this: ========================================================================= # esxcfg-vswif -l Name     Port Group/DVPort   IP Family IP Address                              Netmask                                 Broadcast        Enabled   TYPE vswif0   Service Console     IPv4      192.168.0.75                            255.255.255.0                           192.168.0.255    true      STATIC vswif1   Service Console 2   IPv4      192.168.0.78                            255.255.255.0                           192.168.0.255    false     STATIC ========================================================================= Q.what is the command to get the information about vmkernel ports and its ip address? Answer: esxcfg-vmknic -l Output will appear like this: ========================================================================= # esxcfg-vmknic -l Interface  Port Group/DVPort   IP Family IP Address                              Netmask         Broadcast       MAC Address       MTU     TSO MSS   Enabled Type vmk0       VMkernel            IPv4      192.168.0.110                           255.255.255.0   192.168.0.255   00:50:56:78:7e:73 1500    65535     true    STATIC vmk1       Vmotion             IPv4      192.168.0.77                            255.255.255.0   192.168.0.255   00:50:56:76:42:df 1500    65535     true    S ========================================================================= Q.what is the command to get the information about physical nics installed on ESX server? Answer:  esxcfg-vmknic -l Output will appear like this: ========================================================================= # esxcfg-nics -l Name    PCI      Driver      Link Speed     Duplex MAC Address       MTU    Description vmnic0  02:00.00 e1000       Up   1000Mbps  Full   00:0c:29:85:0d:76 1500   Intel Corporation 82545EM Gigabit Ethernet Controller (Copper) vmnic1  02:02.00 e1000       Up   1000Mbps  Full   00:0c:29:85:0d:80 1500   Intel Corporation 82545EM Gigabit Ethernet Controller (Copper) vmnic2  02:03.00 e1000       Up   1000Mbps  Full   00:0c:29:85:0d:8a 1500   Intel Corporation 82545EM Gigabit Ethernet Controller (Copper) vmnic3  02:04.00 e1000       Up   1000Mbps  Full   00:0c:29:85:0d:94 1500   Intel Corporation 82545EM Gigabit Ethernet Controller (Copper) ======================================================================== Q.What is command to add the new virtual switch named (vswitch3) to our ESX server? Answer: # esxcfg-vswitch -a vswitch3 Now vswitch3 is created without any port group. ====================================================================== Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks vswitch3       64          1           64                1500 PortGroup Name      VLAN ID  Used Ports  Uplinks ======================================================================== Q.What is command to add the new port group  named (mgmt)to vswitch (vswitch 3) ? Answer: # esxcfg-vswitch -A mgmt vswitch3 now port group "mgmt" is added. ========================================================================= Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks vswitch3       64          1           64                1500 PortGroup Name      VLAN ID  Used Ports  Uplinks mgmt                0        0 ========================================================================= Q.How to add the service console port (vswif2) to our newly created port group "mgmt" with the ip addr 192.168.0.79 ? Answer: # esxcfg-vswif -a vswif2 -i 192.168.0.79 -n 255.255.255.0 -p "mgmt" where i is the ip address, n is subnet mask p is to mentione the port group name ========================================================================= vswif2   mgmt                IPv4      192.168.0.79                            255.255.255.0                           192.168.0.255    true      STATIC ========================================================================= Q.How to add the vmkernal port (vmk2)  to our newly created port group "mgmt" with the ip addr 192.168.0.83? Answer: # esxcfg-vmknic -a  -i 192.168.0.83 -n 255.255.255.0 -p "mgmt" ========================================================================= vmk2       mgmt                IPv4      192.168.0.83               255.255.255.0   192.168.0.255   00:50:56:7b:bd:36 1500    65535     true    STATIC ========================================================================= Q.How to change the ip addresss of the existing service console "vswif2"? Answer:  nano /etc/sysconfig/network-scripts/ifcfg-vswif2. Edit the file with your new id address " 192.168.0.255" then save and exit. ====================================================== DEVICE=vswif2 HOTPLUG=yes MACADDR=00:50:56:43:92:be ONBOOT=yes PORTGROUP=mgmt BOOTPROTO=static BROADCAST=192.168.0.255 DHCPV6C=no IPADDR=192.168.0.96 IPV6INIT=no IPV6_AUTOCONF=no NETMASK=255.255.255.0 ====================================================== restart the network service for ip change to take effect: # service network restart Shutting down interface vswif0:                             Shutting down interface vswif2:                             Shutting down loopback interface:                           Bringing up loopback interface:                             Bringing up interface vswif0:                               Another way is to connect to the console of the ESX server and at the shell prompt type in :esxcfg-vswif -d vswif2 This will delete the existing vswif0 and it will give the message about "nothing to flush". then type the below command esxcfg-vswif -a vswif2 -p mgmt -i 192.168.0.97 -n 255.255.255.0 ========================================================================= # esxcfg-vswif -d vswif2 Nothing to flush. # esxcfg-vswif -a vswif2 -p mgmt -i 192.168.0.97 -n 255.255.255.0 Generated New MAC address, 00:50:56:43:92:be for vswif2 Nothing to flush. ========================================================================= Q.How to change  the  ESX host name and default gateway? Answer: edit the below file: nano  /etc/sysconfig/network ====================================== NETWORKING=yes HOSTNAME=ESXTEST1.lab.com GATEWAY=192.168.0.20 GATEWAYDEV=vswif0 IPV6_AUTOCONF=no NETWORKING_IPV6=no ====================================== restart the network service for ip change to take effect: # service network restart Q.How to edit the  ESX host file ? Answer: nano /etc/hosts Edit the file to make entry to your host file. ========================================== 127.0.0.1       localhost ::1             localhost 192.168.0.75    ESXTEST1.lab.com ESXTEST1 ========================================== Q.How to edit the DNS entry of your ESX server? Answer: nano /etc/resolv.conf Edit the file to make changes or to make new entry of dns for your ESX server ======================== name server 192.168.0.20 search lab.com ======================= Q.what is the command to query the firewall ports ? Answer: esxcfg-firewall - q Q.How  to open the port in firewall  (port no 8877, tcp, incoming , name: test3 ? esxcfg-firewall -o 8877,tcp,in,test3 If you are looking for more VMware interview questions Please click  I Keep reading for More Interview questions and answers !!!! Q.What is  VMware HA? Answer: As per VMware Definition, VMware High Availability (HA) provides easy to use, cost effective high availability for applications running in virtual machines. In the event of server failure, affected virtual machines are automatically restarted on other production servers with spare capacity Q.What is AAM in HA? Answer: AAM is the Legato automated availability management.  Prior to vSphere 4.1, VMware's HA is actually re engineered to work with VM's with the help of  Legato's Automated Availability Manager (AAM) software. VMware's vCenter agent (vpxa) interfaces with the VMware HA agent which acts as an intermediary to the AAM software. From vSphere 5.0, it uses an agent called “FDM”  (Fault Domain Manager). Q.What are pre-requites for HA to work? Answer: 1.Shared storage for the VMs running in HA cluster 2.Essentials plus, standard, Advanced, Enterprise and Enterprise Plus Licensing 3.Create VMHA enabled Cluster 4.Management network redundancy to avoid frequent isolation response in case of temporary network issues (preferred not a requirement) Q.What is maximum number of primary HA hosts in vSphere 4.1? Answer: Maximum number of primary HA host is 5. VMware HA cluster chooses the first 5 hosts that joins the cluster as primary nodes and all others hosts are automatically selected as secondar nodes. Q.How to see the list of Primary nodes in HA cluster? Answer: View the log file named "aam_config_util_listnodes.log" under /var/log/vmware/aam using the below command cat /var/log/vmware/aam/aam_config_util_listnodes.log Q.What is the command to restart /Start/Stop HA agent in the ESX host? Answer: service vmware-aam restart service vmware-aam stop service vmware-aam start Q.Where to located HA related logs in case of troubleshooting? Answer: /Var/log/vmware/aam Q.What the basic troubleshooting steps in case of HA agent install failed on hosts in HA cluster? Answer: 1.Check for some network issues 2. Check the DNS is configured properly 3. Check the vmware HA agent status in ESX host by using below commands service vmware-aam status 4.Check the networks are properly configured  and named exactly as other hosts in the cluster. otherwise, you will get the below errors while installing or reconfiguring HA agent. 5. Check HA related ports are open in firewall to allow for the communication Incoming port: TCP/UDP 8042-8045 Outgoing port: TCP/UDP 2050-2250 6. First try to restart /stop/start the vmware HA agent on the affected host using the below commands. In addition u can also try to restart vpxa and management agent in the Host. service vmware-aam restart service vmware-aam stop service vmware-aam start 7. Right Click the affected host and click on "Reconfigure for VMWare HA" to re-install the HA agent that particular host. 8. Remove the affected host from the cluster. Removing ESX host from the cluster will not be allowed untill that host is put into maintenance mode. 9.Alternative solution for 3 step is, Goto cluster settings and uncheck the vmware HA in to turnoff the HA in that cluster and re-enable the vmware HA to get the agent installed. 10. For further troubleshooting , review the HA logs under /Var/log/vmware/aam directory. Q.What is the maximum number of hosts per HA cluster? Answer: Maximum number of hosts in the HA cluster is 32 Q.What is Host Isolation? Answer: VMware HA has a mechanism to detect a host is isolated from rest of hosts in the cluster. When the ESX host loses its ability to exchange heartbeat via management network between the other hosts in the HA cluster, that ESX host will be considered as a Isolated. Q.How Host Isolation is detected? Answer: In HA cluster, ESX hosts uses heartbeats to communicate among other hosts in the cluster.By default, Heartbeat will be sent every 1 second. If a ESX host in the cluster didn't received heartbeat for for 13 seconds from any other hosts in the cluster, The host considered it as isolated and host will ping the configured isolation address(default gateway by default). If the ping fails, VMware HA will execute the Host isolation response Q.What are the different types isolation response available in HA? Power off –  All the VMs are powered off , when the HA detects that the network isolation occurs Shut down – All VMs running on that host are shut down with the help of VMware Tools, when the HA detects that the network isolation occurs.If the shutdown via VMWare tools not happened within 5 minutes, VM's power off operation will be executed. This behavior can be changed with the help of HA advanced options. Leave powered on –  The VM's state remain powered on or remain unchanged, when the HA detects that the network isolation occurs. Q.How to add additional isolation address for redundancy? Answer: By default, VMWare HA use to ping default gateway as the isolation address if it stops receiving heartbeat.We can add an additional values in case if we are using redundant service  console both belongs to different subnet.Let's say we can add the default gateway of SC1 as first value and gateway of SC2 as the additional one using the below value 1. Right Click your HA cluster 2.Goto to advanced options of HA 3. Add the line "das.isolationaddress1 = 192.168.0.1" 4. Add the line "das.isolationaddress2 = 192.168.1.1" as the additional isolation address Q.What is HA Admission control? Answer: As per "VMware Availability Guide", VCenter Server uses admission control to ensure that sufficient resources are available in a cluster to provide failover protection and to ensure that virtual machine resource reservations are respected. Q.What are the 2 types of settings available for admission control? Enable: Do not power on VMs that violate availability constraints Disable: Power on VMs that violate availability constraints Q.What are the different types of Admission control policy available with VMware HA? Answer: There are 3 different types of Admission control policy available.Host failures cluster  tolerates Percentage of cluster resources reserved as fail over spare capacity Specify a fail over host Q.How the Host Failures cluster tolerates admission control policy works? Answer:Select the maximum number of host failures that you can afford for or to guarantee fail over. Prior vSphere 4.1, Minimum is 1 and the maximum is 4. In the Host Failures cluster tolerates admission control policy , we can define the specific number of hosts  that can fail  in the cluster and also it ensures that the sufficient resources remain to fail over all the virtual machines from that failed hosts to the other hosts in cluster. VMware High Availability(HA) uses a mechanism called slots to calculate both the available and required resources in the cluster for a failing over virtual machines from a failed host  to other hosts in the cluster. Q.What is SLOT? Answer: As per VMWare's Definition, "A slot is a logical representation of the memory and CPU resources that satisfy the requirements for any powered-on virtual machine in the cluster." If you have configured reservations at VM level, It influence the HA slot calculation. Highest memory reservation and highest CPU reservation of the VM in your cluster determines the slot size for the cluster. Q.How to Manually define the HA Slot size? Answer: By default, HA slot size is determined by the Virtual machine Highest CPU and memory reservation. If no reservation is specified at the VM level, default slot size of 256 MHZ for CPU and 0 MB + memory overhead for RAM will be taken as slot size. We can control the HA slot size manually by using the following values. There are 4 options we can configure at HA advanced options related to slot size das.slotMemInMB - Maximum Bound  value for HA memory slot size das.slotCpuInMHz - Maximum Bound value for HA CPU slot Size das.vmMemoryMinMB -  Minimum Bound  value for HA memory slot size das.vmCpuMinMHz -  Minimum Bound  value for HA CPU slot size Q.How the "Percentage of cluster resources reserved as failover spare capacity" admission control policy works? Answer: In the Percentage of cluster resources reserved as failover spare capacity admission control policy, We can define the specific percentage of total cluster resources are reserved for failover.In contrast to the "Host Failures cluster tolerates admission control policy", It will not use slots. Instead This policy calculates the in the way below 1.It calculates the Total resource requirement for all Powered-on Virtual Machines in the cluster  and also calculates the total resource available in host for virtual machines. 2.It calculates the current CPU and Memory Failover capacity for the capacity. 3.If the current CPU and Memory Failover capacity for the cluster < configured failover capacity (ex 25 %) 4.Admission control will not allow to power on the virtual machine which violates the availability constraints. Q.How the "Specify a failover host" admission control policy works? Answer: In the Specify a failover host" admission control policy, We can define a specific host as a dedicated failover host. Whenisolation response is detected, HA attempts to restart the virtual machines on the specified failover host.In this Approach, dedicated failover hist will be sitting idle without actively involving or not participating in DRS load balancing.DRS will not migrate or power on placement of virtual machines on the defined failover host. Q.What is VM Monitoring status? Answer: HA will usually monitors ESX hosts and reboot the virtual machine in the failed hosts in the other host in the cluster in case of host isolation but i need the HA to monitors for Virtual machine failures also. here the feature called VM monitoring status as part of HA settings.VM monitoring restarts the virtual machine if the vmware tools heartbeat didn't received with the specified time using Monitoring sensitivity. Q.What is VMware Fault Tolerance? Answer: VMware Fault Tolerance is a component of VMware vSphere and it provides continuous availability to applications by preventing downtime and data loss of Virtual machines in the event of ESX server failures. Q.What is the name of the technology used by VMware FT? Answer: VMware FT using a technology called vLockstep technology Q.How do i check my host for FT compatibility from vSphere client? Answer: One way from vSphere client is to run the cluster complaince check from profile compliance tab of  your cluster. The below checks as specified below will be performed as part of the compliance check. Validate that Fault Tolerancelogging NIC speed is at least 1000 Mbps. Validate that power management is supported on the host Validate that Fault Tolerance logging is enabled. Validate that VMotion NIC speed is at least 1000 Mbps. Validate that all the hosts in the cluster have the same build for Fault Tolerance Validate that the host hardware supports Fault Tolerance. Validate that VMotion is enabled. Validate that at least one shared datastore exists Q.What is FT Logging Traffic? Answer: FT logging is the one of option in VMkernel port setting which is similar to enable vmotion option in the vmkernel port. when FT is enabled for the virtual machine, all the inputs (disk read.. wirte,etc..) of the primary virtual machine are recorded and sent to the secondary VM over via FT logging enabled VMkernel port. Q.How to Enable FT Logging in VMkernel Port? Answer: GO the ESX host -> Configuration-> Networking -> Properties of Virtual switch with the VMkernel portgroup configured Q.How do you configure or enable FT for the virtual machine ? Answer: FT can be enabled only per virtual machine basis not at the cluster or ESX level. Right-click the virtual Machine -> Fault Tolerance -> Turn on Fault Tolerance Q.How does the FT enabled virtual machine will be differentiated with non FT VM's in vSphere client? Answer: FT Enabled Virtual machine will appear in Dark Blue colour as compared to non-protected virtual machines. By default, Only Primary virtual machine will appear under the cluster and ESX host. To take a look at the secondary VM , Go to Virtual Machines tab of the Cluster or Host. Q.How Does VMware Fault Tolerance Work? Answer: When you enable Fault Tolerance for the virtual machine, a secondary virtual machine will be created to work with the primary virtual machine in which you have enabled FT. The primary and secondary virtual machine resides on a different ESX hosts in the cluster. Whatever the events or actions performed  by the primary VM will be transmitted via gigabit Ethernet network to be replayed by the secondary virtual machine using VLockstep technology. Eventhough both the primary and secondary virtual machines appear as a single entity  and access a common disk, both  running with the single IP address, MAc address but writes are only performed by the primary virtual machine.The primary and secondary virtual machines sends heartbeat  between each other frequently with millisecond intervals to the check for the availability. If either of the virtual machine loses the heartbeat, other virtual machine will take over the  primary virtual machine role immediately. Q.What happens when you enabled Fault Tolerance for your virtual machine? Answer: When you enable Fault Tolerance for the virtual machine, a secondary virtual machine (live shadow image of the primary) will be created to work with the primary virtual machine in which you have enabled FT.  The primary and secondary virtual machine resides on a different ESX hosts in the cluster. Q.What will happen when the ESX host of primary VM failed? Answer: When a failure is detected on the primary VM's ESX host, the secondary virtual machine which is running on the another ESX server in the same cluster will takes the place of the first one with the least possible interruption of service. Q.If vCenter is down, will the FT work? Answer: vCenter server is only required to enable FT on the virtual machine.once it is configured, vCenter is not required to be in online for FT to work. FT failover between primary and secondary will occure even if the vCenter is down. Q.How does Vmware FT differs from VMware HA? Answer: 1.VMware HA is enabled per cluster basis but FT is enabled per VM basis. 2. In case of ESX host failure, virtual machines in the  failed host are restarted and powered-on on  the other active hosts in HA cluster. So the restart duration of the virtual machine is the downtime for the virtual machine in HA cluster. But in FT enabled virtual machine, there is no downtime. In case of host failure, secondary VM will become primary and  continuing the execution from the exact point where the primary VM is left off or failed. It happens automatically without data loss, without downtime and with a little delay. Users will not see any interruption. Q.What are the three port groups present in ESX server networking Answer:

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

Q.What is the use of a Port Group? Answer: The port group segregates the type of communication. Q.What are the type of communications which requires an IP address for sure ? Answer: Service Console and VMKernel (VMotion and iSCSI), these communications does not happen without an ip address (Whether it is a single or dedicated) Q.In the ESX Server licensing features VMotion License is showing as Not used, why? Answer: Even though the license box is selected, it shows as "License Not Used" until, you enable the VMotion option for specific vSwitch Q.How the Virtual Machineort group communication works ?  Answer: 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 Q.Does the vSwitches support VLAN Tagging? Why? Answer: 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. :) Q.What is Promiscuous Mode on vSwitch ? What happens if it sets to Accept? Answer: 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. Q.What is MAC address Changes ? What happens if it is set to Accept ? Answer: 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. Q.What is Forged Transmits ? What happens if it is set to Accept ? Answer: 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. Q.What are the core services of VC ? Answer: VM provisioning , Task Scheduling and Event Logging Q.Can we do vMotion between two datacenters ? If possible how it will be? Answer: Yes we can do vMotion between two datacenters, but the mandatory requirement is the VM should be powered off. Q.What is VC agent? and what service it is corresponded to? What are the minimum req's for VC agent installation ? Answer: 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. Q.How can you edit VI Client Settings and VC Server Settings ? Answer:  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 Q.What are the files that make a Virtual Machine  ? Answer: .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 Q.What are the devices that can be added while the virtual Machine running Answer:  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 Q.How to set the time delay for BIOS screen for a Virtual Machine? Answer: Right Click on VM, select edit settings, choose options tab and select boot option, set the delay how much you want. Q.What is a template ? Answer: 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. Q.What to do to customize the windows virtual machine clone,? Answer: copy the sysprep files to Virtual center directory on the server, so that the wizard will take the advantage of it. Q.What to do to customize the linux/unix virtual machine clone,? Answer: VC itself includes the customization tools, as these operating systems are available as open source. Q.Does cloning from template happens between two datacenters ? Answer: Yes.. it can, if the template in one datacenter, we can deploy the vm from that template in another datacenter without any problem. Q.What are the common issues with snapshots? What stops from taking a snapshot and how to fix it ? Answer: 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. Q.What are the settings that are taken into to consideration when we initiate a snapshot ? Answer: 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) Q.What are the requirements for Converting a Physical machine to VM ? Answer: 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 Q.What is VMWare consolidated backup ? Answer: It is a backup framework, that supports 3rd party utilities to take backups of ESX servers and Virtual Machines. Its not a backup service. contact for more on VMWare Online Training