ISOLATE THE PROBLEM
step1: Determine if your network interface card(NIC) installed in your computer is working fine using the PING command.
To do this, open up cmd. Type “cmd” in the Run field, this will show the command prompt interface.
Type “ping loopback”.
You will know if your NIC is faulty if you will see “Time out” replies and lost packets. The above result indicates a working NIC.
step2: Determine if your gateway is the problem, usually your router if you are using one. This time Ping your gateway. To know your gateway address type “ipconfig” in the same cmd window.
Again look for “Timed out” replies and packet loss. The above example shows a working good gateway.
step3: Determine if your ISP is the problem. In the same procedures above ping a website of your choosing.
Above example pings http://www.facebook.com.
step4: Sometimes the problem is your Domain Name Server(DNS) or WINS. For local computer its the LMHOST file. You know this is the problem when you can ping the IP address of the website or network computer but not its name.
Try pinging facebook using its IP address. Type “ping 220.127.116.11“. To know IP addresses of a specific website click here.
step5: Resolve DNS/WINS issues.
1. Type nbtstat -R at the command prompt, to purge the name cache and reload it from the LMHOSTS file.
2. Check to make sure that the computer is configured with the proper DNS or WINS entries, and that the DNS or WINS servers are available.