VMWare interview questions and answers

What is Service Console?

The service console is developed based up on Redhat Linux Operating system, it is used to manage the VMKernel

What are the basic commands to troubleshoot  connectivity between vSphere Client /vCenter to ESX server?

service mgmt-vmware restart  (restarts host agent(vmware-hostd) on vmware esx server)

service vmware-vpxa restrat (restarts Vcenter agent service)

service network restart (restarts management networks on ESX)

What is vCenter Agent?

VC agent is an agent installed on ESX server which enables communication between VC and ESX server. This Agent will be installed on ESX/ESXi will be done when you try to add the ESx host in Vcenter.

What is the command used to restart SSH, NTP & Vmware Web access?

Service sshd restart

Service ntpd restrat

Service vmware-webaccess restart

What are the types of Ports groups in ESX/ESXi?

There are 3 types of port groups in ESX

1.Service console port group

2.VMkernel Port group

3. Virtual machine port group

There are only 2 types of port group in ESXi

1. Vmkernel Port group

2.Virtual Machine Port group

What is VMKernel ?

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 Redhat Linux OS not VMkernel.

What is the use of Service Console port ?

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.

What is the use of VMKernel Port ?

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.

What is the use of Virtual Machine Port Group?

Virtual Machine port group is used by Virtual machine communication.

How Virtual Machine communicates to another servers in Network ?

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.

What is the default number of ports configured with the Virtual Switch?

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.

What are the different types of Partitions in ESX server?

/ -root

Swap

/var

/Var/core

/opt

/home

/tmp

What are the security options available for ESX vswitch?

Promiscuous Mode - Reject

MAC Address changes - Accept

Forged Transmits - Accept

What is Promiscuous Mode ?

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.

What is MAC Address changes?

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.

What is Forged Transmits ?

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.

What is a VLAN ?

A VLAN is the Virtual LAN which is used to broke down the Broadcast traffic into many logical groups. Basically, one physical switch comprise of one broadcast domain. VLAN used to separate the one broadcast domain into many small pieces to separate the networks within the broadcast domain.

What are the types of VLAN tagging in Vsphere?

There are 3 types of VLAN tagging available in Vsphere.

1.Virtual Switch Tagging (VST)

2.External Switch Tagging (EST)

3.Virtual Guest Tagging (VGT)

What are the Traffic Shaping policies available in the Vswitch?

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

What are the Load balancing policies available in vswitch?

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.

What are THE TYPES for Network Failover Detection settings?

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.

What is the command to  check the IP address along with the detailed network cards assigned to the esx server?

Ifconfig -a

utput 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

=========================================================================

[root@ESXTEST1 etc]# 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

=========================================================================

what is the command to check the ESX vswitch details, port group and its ip address?

Esxcfg-vswitch -l

Outuput will appear like this:

=========================================================================

[root@ESXTEST1 ~]# 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.

What is command to get the information about Service console ports and its IP address assigned to it?

esxcfg-vswif -l

Output will appear like this:

=========================================================================

[root@ESXTEST1 ~]# 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

=========================================================================

what is the command to get the information about vmkernel ports and its ip address?

esxcfg-vmknic -l

Output will appear like this:

=========================================================================

[root@ESXTEST1 ~]# 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

=========================================================================

what is the command to get the information about physical nics installed on ESX server?

esxcfg-vmknic -l

Output will appear like this:

=========================================================================

[root@ESXTEST1 sbin]# 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)

========================================================================

What is command to add the new virtual switch named (vswitch3) to our ESX server?

[root@ESXTEST1 sbin]# 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

========================================================================

What is command to add the new port group  named (mgmt)to vswitch (vswitch 3) ?

[root@ESXTEST1 sbin]# 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

=========================================================================

How to add the service console port (vswif2) to our newly created port group "mgmt" with the ip addr 192.168.0.79 ?

[root@ESXTEST1 sbin]# 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

=========================================================================

 How to add the vmkernal port (vmk2)  to our newly created port group "mgmt" with the ip addr 192.168.0.83?

[root@ESXTEST1 sbin]# 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

=========================================================================

How to change the ip addresss of the existing service console "vswif2"?

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:

[root@ESXTEST1 sysconfig]# service network restart

Shutting down interface vswif0:                            [  OK  ]

Shutting down interface vswif2:                            [  OK  ]

Shutting down loopback interface:                          [  OK  ]

Bringing up loopback interface:                            [  OK  ]

Bringing up interface vswif0:                              [  OK  ]

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

=========================================================================

[root@ESXTEST1 etc]# esxcfg-vswif -d vswif2

Nothing to flush.

[root@ESXTEST1 etc]# esxcfg-vswif -a vswif2 -p mgmt -i 192.168.0.97 -n 255.255.255.0

[2011-09-17 19:35:46 'Vnic' warning] Generated New MAC address, 00:50:56:43:92:be for vswif2

Nothing to flush.

=========================================================================

How to change  the  ESX host name and default gateway?

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:

[root@ESXTEST1 sysconfig]# service network restart

 How to edit the  ESX host file ?

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

==========================================

How to edit the DNS entry of your ESX server?

nano /etc/resolv.conf

Edit the file to make changes or to make new entry of dns for your ESX server

========================

nameserver 192.168.0.20

search lab.com

=======================

 what is the command to query the firewall ports ?

esxcfg-firewall - q

How  to open the port in firewall  (port no 8877, tcp, incoming , name: test3 ?

esxcfg-firewall -o 8877,tcp,in,test3

What is Clustering? How it works?

What is Clustering?

Clustering is a technology in which one or more computers work together as a single instance by sharing their resources. Clustering is used mainly for redundancy of the services hosted on it. In other words, in a cluster all the hosts are work together, if one of the host fails all the services hosted on it comes online immediately on to another host with out any downtime. Apart from the redundancy a cluster is used for load balancing also, in this case what ever the load comes to the cluster is shared by all the hosts in it.

What are the types of Clusters and How do we configure them ?

Clustering is two types, Active/Active and Active/Passive.

Active/Active : In this scenario all the hosts configured in the cluster takes all the load comes to that cluster, and if any one of the host fails the remaining hosts share the requests to make it online all the time. If you have same copies of application configured on multiple hosts this type of clustering is applicable.

Active/Passive : In this scenario load balancing is not works, as at any point of time only one host receives all the requests, and if any of the host fails the remaining hosts takes those services and make them available online. That means, only one host is active at any point of time and the other one is passive.

What are the requirements to configure a cluster and How it works?

There are so many requirements to configure the cluster, but all those requirements are inter dependable on each other. And these requirements (we call them as resources in clustering), are shared between all the hosts, that means these should be available to all the hosts in the cluster. for example, SAN storage resource, the storage which configured in network and is accessible by all hosts.  In the same way all the resources are accessible by all the hosts in a cluster. If one of the host fails, all these resources are moved to another host. In detail, at a particular time one host is accessing these resources, at that time those are locked by that particular host, whenever this host fails, the lock was released and those resources are locked by another host. But in active/active clusters these resources have multiple copies as multiple instances on all hosts.

PERMISSION

CHMOD is used to change permissions of a file.

        PERMISSION      COMMAND   

         U   G   W
        rwx rwx rwx     chmod 777 filename      
        rwx rwx r-x     chmod 775 filename
        rwx r-x r-x     chmod 755 filename
        rw- rw- r--     chmod 664 filename
        rw- r-- r--     chmod 644 filename

        U = User 
        G = Group 
        W = World

        r = Readable
        w = writable
        x = executable 
        - = no permission

Here is another way of looking at it: 



Permissions:

400     read by owner
040     read by group
004     read by anybody (other)
200     write by owner
020     write by group
002     write by anybody
100     execute by owner
010     execute by group
001     execute by anybody

To get a combination, just add them up. For example, to get read, write, execute by owner, read, execute, by group, and execute by anybody, you would add 400+200+100+040+010+001 to give 751.

Repair Outlook 2007 PST with ScanPST

Are you having problems with your PST (personal folders) in Outlook 2007? If so, there is a simple way to take care of any issue or corruption you may have with your PST. Outlook automatically includes a PST repair tool called ScanPST.

ScanPST can save your PST if you see this message:

FileName.pst file could not be opened. The file may not be compatible with this version of Outlook or it may be corrupted.

In Windows Vista, you may see an error message when you start Outlook 2007 that says:

<FileName>.pst file could not be opened

NOTE: These two things are very important to repair your PST, so do them first.

1. Make sure Outlook 2007 is closed
2. Locate the PST file that you will be repairing and note that location so you can get back to it later.

Once you have completed the previous two steps, navigate to C:\Program Files\Microsoft Office\Office12 (where “C” is the letter of your hard drive) and find the SCANPST utility.

Double click on the ScanPST utility and the Repair window will open. Click the “Browse” button and navigate to the location where your PST lives and select the PST you want to repair.

The name of your PST will show in the window. Click the “Start” button to begin scanning your PST. There is no need to worry as this only does a scan on your PST and does NOT make any changes. This will only detect any problems.

The scan will go through 8 steps. The amount of time it will take to complete, depends on the size of your PST.

When the scan completes you will see the summary window of what the scan found. The important part is that it will tell you if you have any error in your PST.
Now you can repair your corrupt PST. I highly recommend making a backup of your PST before you repair just to be safe. So check the box to make a backup and click the “Browse” button to select a location for your backup. (Save the backup to your desktop since the repair will be fine and you can delete the backup when you are done.) Now click the “Repair” button to repair the PST.

The repair will process your PST and complete and you will see a confirmation message that the repair is complete.

You can now delete the backup that you made and saved to your desktop. Open Outlook 2007 and you shouldn’t see any more issues with your PST and Outlook 2007.

10 Windows 7 commands every administrator should know

1: System File Checker

Malicious software will often attempt to replace core system files with modified versions in an effort to take control of the system. The System File Checker can be used to verify the integrity of the Windows system files. If any of the files are found to be missing or corrupt, they will be replaced. You can run the System File Checker by using this command:

sfc /scannow

2: File Signature Verification

One way to verify the integrity of a system is to make sure that all the system files are digitally signed. You can accomplish this with the File Signature Verification tool. This tool is launched from the command line but uses a GUI interface. It will tell you which system files are signed and which aren’t. As a rule, all the system files should be digitally signed, although some hardware vendors don’t sign driver files. The command used to launch the File Signature Verification tool is:

sigverif

3: Driverquery

Incorrect device drivers can lead to any number of system problems. If you want to see which drivers are installed on a Windows 7 system, you can do so by running the driverquery tool. This simple command-line tool provides information about each driver that is being used. The command is:

driverquery

If you need a bit more information, you can append the -v switch. Another option is to append the -si switch, which causes the tool to display signature information for the drivers. Here’s how they look:

driverquery -v

driverquery -si

4: Nslookup

The nslookup tool can help you to verify that DNS name resolution is working correctly. When you run nslookup against a host name, the tool will show you how the name was resolved, as well as which DNS server was used during the lookup. This tool can be extremely helpful when troubleshooting problems related to legacy DNS records that still exist but that are no longer correct.
To use this tool, just enter the nslookup command, followed by the name of the host you want to resolve. For example:

nslookup dc1.contoso.com

5: Ping

Ping is probably the simplest of all diagnostic commands. It’s used to verify basic TCP/IP connectivity to a network host. To use it, simply enter the command, followed by the name or IP address of the host you want to test. For example:

ping 192.168.1.1

Keep in mind that this command will work only if Internet Control Message Protocol (ICMP) traffic is allowed to pass between the two machines. If at any point a firewall is blocking ICMP traffic, the ping will fail.

6: Pathping

Ping does a good job of telling you whether two machines can communicate with one another over TCP/IP, but if a ping does fail, you won’t receive any information regarding the nature of the failure. This is where the pathping utility comes in.
Pathping is designed for environments in which one or more routers exist between hosts. It sends a series of packets to each router that’s in the path to the destination host in an effort to determine whether the router is performing slowly or dropping packets. At its simplest, the syntax for pathping is identical to that of the ping command (although there are some optional switches you can use). The command looks like this:

pathping 192.168.1.1

7: Ipconfig

The ipconfig command is used to view or modify a computer’s IP addresses. For example, if you wanted to view a Windows 7 system’s full IP configuration, you could use the following command:

ipconfig /all

Assuming that the system has acquired its IP address from a DHCP server, you can use the ipconfig command to release and then renew the IP address. Doing so involves using the following commands:

ipconfig /release

ipconfig /renew

Another handy thing you can do with ipconfig is flush the DNS resolver cache. This can be helpful when a system is resolving DNS addresses incorrectly. You can flush the DNS cache by using this command:

ipconfig /flushdns

8: Repair-bde

If a drive that is encrypted with BitLocker has problems, you can sometimes recover the data using a utility called repair-bde. To use this command, you will need a destination drive to which the recovered data can be written, as well as your BitLocker recovery key or recovery password. The basic syntax for this command is:

repair-bde <source> <destination> -rk | rp <source>

You must specify the source drive, the destination drive, and either the rk (recovery key) or the rp (recovery password) switch, along with the path to the recovery key or the recovery password. Here are two examples of how to use this utility:

repair-bde c: d: -rk e:\recovery.bek

repair-bde c: d: -rp 111111-111111-111111-111111-111111-111111

9: Tasklist

The tasklist command is designed to provide information about the tasks that are running on a Windows 7 system. At its most basic, you can enter the following command:

tasklist

The tasklist command has numerous optional switches, but there are a couple I want to mention. One is the -m switch, which causes tasklist to display all the DLL modules associated with a task. The other is the -svc switch, which lists the services that support each task. Here’s how they look:

tasklist -m

tasklist -svc

10: Taskkill

The taskkill command terminates a task, either by name (which is referred to as the image name) or by process ID. The syntax for this command is simple. You must follow the taskkill command with -pid (process ID) or -im (image name) and the name or process ID of the task that you want to terminate. Here are two examples of how this command works:

taskkill -pid 4104

taskkill -im iexplore.exe

How to remove Active Desktop Recovery screen

1. Go to Run and type regedit
2. Now navigate to this path –HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Desktop\SafeMode\Components
3. You would find a key named DeskHtmlVersion
4. Right click the key and select Modify
5. Under the label Base, select the radio button Decimal
6. Change Value data to 0
7. Click OK

This should do the trick. If the screen doesn’t go then try restarting your PC for the changes to take effect.