2. If you server stopped working you should inform the users of the server and you should start working on fixing the error.
3. If a single client computer stopped working or disconnected from the network, ask the user of that computer that what recent changes cause the server to stop working such as newly installed software or games, service pakcs, internet software, new hardware or any other thing.
4. Check the physical network connectivity. The most network problems arise due to the physical layers failure.
5. Check all the network cable connections. You can start at the NIC and check if the green light is blinking then check the hub and see if the computer is getting the link across the cable.
6. Get a cable tester to check the connectivity of the cables.
7. Finally start pinging the network both Windows and Linux have the PING command. You can use ping command in this way start > Run > cmd > type "ping" then IP address of the other computer.
How to Troubleshoot Connectivity problems
1. Use the ping command to test the basic connectivity. By using the ping command you can isolate network hardware problems and incompatible configurations. By using the path ping you can detect packet loss.
2. If you want to see the Ping's statistics then you ping -t command and press enter to continue and if you want to stop then press CTRL+BREAKTo watch Ping statistics, use the ping -t command. To see statistics and continue, press CTRL+BREAK. To stop, press CTRL+C.
3. If you remote system is across the delay link, such as satellite link responses may take longer.
4. Check the event logs for network card and other hardware and software configurations and connectivity related entries.
5. Check whether the NIC card is on the Microsoft Hardware Compatibility List (HCL).
6. Check other computers that use the same gateway and are plugged into the same hub or switch and if these computers do not show any network connectivity problem then the problem is on the only one computer.
7. Contact the vendor of each NIC and motherboard and update the BIOS.
8. Replace the network adapter of the system with the good configured system and see if the same error arise again.
SOME BASIC TROUBLESHOOTING TIPS
Make sure that you have the same IP address schme, same subnet mask, same default gateway, same DNS and DHCP settings for all the computers in a network. Also make sure that you can ping the other computers by their IP address as well as by their name. Make sure that you have the same workgroup or domain name for all the computers. For troubleshooting and administrative purposes turn off all the firewalls. Use the same administrative password for troubleshooting on all the computers. Try pinging the other computers this will test the TCP/IP connectivity. You can use the ping command in this format ping 10.100.100.1 and if you can get the reply from the other computer then the connectivity is ok and if get the time out error then there must me some error in the connectivity or error in configurations.
Issues in Finding websites
If you find any problem in finding the websites then ping the website name rather than the IP address and this will determine if your DNS entry is corret or working for example ping www.google.com. If this works then problem must be in your web browser due to misconfigurations. You should check the proxy server settings of your browsers and clear the cache and temporary internet files.
Issues in Pinging a computer
If you can't ping the computer by its name then check the DNS IP address in your network or dial-up setup.
Issues in connecting to the other device on Local Area Network
If you can ping all the other computers but are not allowed access then make sure that you are using the same user name and password assigned by the same domain controller. Try connecting to the computer using start > run > server name where serve name is the name of the server you want to connect to. Also add the computer name and it's IP address in the LMHOSTS file, which resides at Windows\System32\Drivers directory for Windows 2000 or XP.
Issues in Network Connectivity.
If a computer is unable to connect to a network or see other computers in a network it may be necessary to troubleshoot the network. Due to the following reasons you network may not work.
1. Network card not connected properly
2. Bad NIC card drive's settings
3. Firewall preventing computers from seeing each other.
4. Connection related issues.
5. Bad network hardware.
Because of the large variety of the network configurations, setup, software, hardware operating systems etc not all the information may apply to your network or operating system. First of all verify that the network cable of each computer is properly connected, one end to the NIC card, which is plugged into the computer and one end to the Hub or switch. Ensure that the green light is blinking on the NIC, this shows that the NIC is either receiving or sending the data. On the other hand if the card does not have any lights or has orange or red lights, then is possible that either the NIC adapter is bad or not connected properly.
Make sure that the cables are properly connected to the hub or swtich. Make sure that the newly installed NIC adapter is not conflicting with the other NIC cards on the network and a unique IP address is assigned to each NIC card. If there is some conflict then the device manager may identify the conflicting card. Furthermore, make sure that the NIC is capable of pinging or seeing itself by the ping command. If you are on the TCP/IP network, make sure that the correct protocols are installed. If you are using a firewall, ensure all the ports required are open. While troubleshooting you can close the firewall program so that they there should not occur any conflict.
TCP/IP Configuraitons Checking
The first step in the troubleshooting process is to check the TCP/IP settings. You can check it by using the IPCONFIG/All command on the command prompt. You will see the configuration results. If you see a blank configuration for a card this means then the card is not assigned any IP address. You can assign the IP address manually or via DHCP server. If you are using the DHCP server for assigning the IP addresses then you can use the following commands to get and release the IP address.
If the computer is still unalbe to obtain an IP address, then there are several things that can causing this problem such as bad network cable or NIC card, DHCP server might have assigned all the IP addresses from its pool, misconfigured TCP/IP settings, incorrect user name and password. You can try to add a new well configured machine to the replace the malfunctioning machine to see if the new machine is working with its settings. Also see if the driver of the NIC is properly installed or not. In case of driver's problem go to the vendor's website and install a new exact driver for the NIC.