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Beware of Trojan Horse!



 

 

 

 

Simple Network Troubleshooting Tips

Here are a few tips that you can try to fix your network. Please follow the steps listed below in the same sequence.

1) If you have installed any firewall like Zone Alarm or Norton Personal Firewall, please disable it.

Windows XP comes with "Internet Connection Firewall". Disable it temporarily.

Most network problems may be due to improperly configured firewalls. I have encountered cases like Windows file sharing fails to work when the firewall on the PC is improperly configured.

2) Note the TCP/IP settings from the PC that fails to connect to the network. Compare this settings with the other good PC. Ensure it is using the same network address and subnet mask.

Use Winipcfg for Win9x PCs. For Win XP or Win 2000, use ipconfig from command prompt.

3) "ping itself then ping others" method

The problematic PC has an IP address of 192.168.1.1, named hulk.

"ping 127.0.0.1"
"ping localhost"
"ping 192.168.1.1"
"ping hulk"

If either one above got no reply, TCP/IP stack got problem.

For WinXP, you need to reset the TCP/IP stack with:

netsh int ip reset resetlog.txt

Next ping other PCs on the network:

"ping 192.168.1.2"
"ping neighbour"

"neighbour" is the name of the other PC. If ping fails with name, that means there is a NetBIOS name resolution failure. Make sure that NetBIOS over TCP/IP is enabled. You will get this errors:

Unknown host <name> or Ping request could not find host <name>

If the problematic PC can ping the other PC but cannot access the internet, then you need to check the default gateway.

Make sure the TCP/IP default gateway setting is set correctly.

ping the gateway IP address (if fails, the default gateway is down)

ping the dns IP address (if fails, the dns server is down)

You can set it to the DNS IP address provided by your ISP. It is unlikely that the ISP's DNS server to be down.

ping external website IP address (ISP proxy down or the website is down)

ping www.blarblar.com (DNS server down or website down)

 

Good Luck!

Last Update: 03 March 2004