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troubleshoot the network on a windows machine

posted Dec 9, 2010, 1:50 AM by d graham   [ updated Dec 9, 2010, 5:48 PM ]
On a Windows XP, Vista or 7 machine, most networking problems can be resolved by ensuring your Ethernet cable is plugged in or that your wifi card is turned on and configured. On a laptop there may be a physical switch on the front, side or face of the machine, or you may be able to turn the wifi on and off using the Fn button and one of the F-buttons. If you are sure the network is on, try right clicking on the network in the right hand corner of your screen and selecting "repair" test your connection, as often this fixes a Windows network error.

To determine the reason the internet is not working we must first determine the point of failure.

Try to ping a website on the internet(be aware that some domains explicitly block ping requests and will always fail, notoriously microsoft.com is known to do this):

ping www.google.com

The response should look like this:

Pinging www.l.google.com [74.125.155.105] with 32 bytes of data:
Reply from 74.125.155.105: bytes=32 time=86ms TTL=51
Reply from 74.125.155.105: bytes=32 time=94ms TTL=51
Reply from 74.125.155.105: bytes=32 time=86ms TTL=51
Reply from 74.125.155.105: bytes=32 time=91ms TTL=51

Ping statistics for 74.125.155.105:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 86ms, Maximum = 94ms, Average = 89ms

If you get a response that says failed try to ping the IP address: 74.125.155.105

Pinging 74.125.155.105 with 32 bytes of data:
Reply from 74.125.155.105: bytes=32 time=112ms TTL=51
Reply from 74.125.155.105: bytes=32 time=94ms TTL=51
Reply from 74.125.155.105: bytes=32 time=91ms TTL=51
Reply from 74.125.155.105: bytes=32 time=86ms TTL=51

Ping statistics for 74.125.155.105:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 86ms, Maximum = 112ms, Average = 95ms

If that works, your computer is unable to resolve hosts names, and probably needs to have DNS server settings fixed, possibly you are infected with a virus or spyware. If pinging google's IP address fails, you are unable to reach the outside world.

Obtain your gateway IP address, by going to Start > Run > CMD and typing ipconfig /all

Ensure this gateway address is what it should be (perhaps by checking another working computer on the same network) and then try to ping the gateway. This may look like: ping 10.1.10.1 or ping 192.168.0.1 and will vary from network to network. If you are able to reach the gateway, but not the internet the problem most likely is with your ISP. Sometimes resetting a cable or dsl modem will fix this type of connection problem.

If you are unable to ping the gateway, the problem is with your local workstation. Try to ping yourself by using the loopback connection: ping 127.0.0.1

Pinging 127.0.0.1 with 32 bytes of data:
Request timed out.
Reply from 127.0.0.1: bytes=32 time=2ms TTL=128
Request timed out.
Request timed out.

Ping statistics for 127.0.0.1:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),
Approximate round trip times in milli-seconds:
    Minimum = 2ms, Maximum = 2ms, Average = 2ms

Some of the loopback connection pings may fail, even if you are able to access the internet, so don't be too worried about this step.  If pinging on the loopback fails, often this is due to overzealous firewall settings. Try closing the firewall or adjusting to a less restricted mode to see if the firewall could be blocking all systems access to the network. If the loopback connection works, and you are using DHCP to assign IP addresses on the network, try to release and renew the local DHCP lease by going to Start > Run > CMD and then typing:

ipconfig /release
ipconfig /renew

For a wireless connection ensure you have the proper password and have selected the proper type of security: Open,WEP, WPA, or WPA2

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