Troubleshooting TCP/IP Networks

The purpose of this section is to give general tips
on troubleshooting your TCP/IP LAN or Internet Connection

The basics for troubleshooting are:
1. Make sure you have the same IP scheme (e.g. 192.168.0.x).
2. Make sure you have the same Subnet Mask, Gateway, and DNS IP addresses
3. Make sure you can ping the other computers by IP ADDRESS
4. Make sure you can ping the other computers by NAME
5. Make sure you have the same workgroup name (watch for trailing spaces)
6. For troubleshooting purposes, uninstall any 3rd party firewall software and  turn off XP’s built in one. You can always add more complexity after you get it working.
7. With Windows2000, XP and Vista, make sure you have the same username and password as the person logging onto the other computers. The default setting for all but the Home Versions is to require a password for network access.
8. More details about how to network XP can be found at:
WindowsXP Networking
9. More details about how to network Vista can be found at:
Vista Networking
10. Basically keep things simple. Remove any unnecessary firewalls, protocols or other configurations the complicate the troubleshooting process. You can add them back in later after you get things working.

How to Determine Your IP Address
1. For Win9x ( Start / Run / Command )
2 For Windows2000, XP and Vista ( Start / Run / CMD )
3. Then run IPCONFIG /ALL
4. This will give a text display of all the IP information for any network adapters.
5. With Win98 you can also run WINIPCFG to get a graphic of your TCP/IP settings

WinIPCfG Screen

How to Ping
1. For Win9x ( Start / Run / Command )
2 For Windows2000, XP and Vista ( Start / Run / CMD )
3. The syntax is: PING IP or PING NAME
4. PING IP – An example would be PING 192.168.0.1
5. PING NAME – An example would be PING server or PING www.yahoo.com

If you do not get a reply, and there is no firewall software installed, your network configuration, modem, Ethernet card, or cabling is probably at fault
  • Triple check all your network settings.
  • If you have Win9x, you can run WINIPCFG to get a graphic of your TCP/IP settings.
  • Click on the More Info tab to bring up a screen similar to the one below.
  • If you have Windows2000, XP or Vista, open up a command window (Start / Run / CMD), then run IPCONFIG /ALL. This will give a text display of all the IP information for any network adapters.
  • If you have a network adapter, make sure that the adapter is set up correctly.
  • Also check to see if any link status lights on your adapter are lit.
  • If you are on a local LAN, see if you can use another known working computer’s network drop, cabling, and network card.
  • Make sure your Dial-Up Network settings are all correct. It is easy to miss an item.

If your PING works but you are having problems finding sites on the Internet
  • Try PINGing a name rather than an IP address.
  • This will determine if your DNS entry is correct or working.
  • For example: PING www.yahoo.com
  • If this works, then likely your web browser is misconfigured. Make sure you do not have an incorrect proxy server setting in your Web Browser
  • It could also be a corrupt winsock registry entry

If you can’t Ping a Computer Name
  • Check the DNS IP address in your Network or Dial-Up Icon’s setup
  • If you are only using an ISP and not connected to a local LAN, you only need a DNS entry in the Dial-Up Icon.

If you are on a LAN but cannot connect to any other devices
  • If you can ping all the other computers on your network but are not allowed access:
  • Make sure you have the same username and password defined on any NT based computer (NT 4, Windows2000 and XP), that are logging into the other computers.
  • Try connecting to the computer using Start \ Run and enter \\Servername where Servername is the name of the server you want to connect to.
  • Add the Computer and it’s IP address to the LMHOSTS file. This is a straight text file that resides in the Windows directory (for Win9x) or the Windows\System32\drivers\etc directory (for Windows2000 or XP) and has the format IP_Address   Computer_Name
  • Don’t rely on the Network Neighborhood to always show you a list of computers. Browsing is fairly complicated issue and has a lot of places for failure. If you need to have resources available, create shortcuts on your desktop instead
  •  If you have Win95, make sure you get the Winsock update from Microsoft before connecting to a Windows2000 or XP computer.

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