Open a terminal window, or a 'DOS prompt' in MS Windows

Push the [start] button, then the [Run...] button and type cmd at the Open... prompt

In the DOS window, type ping and the system or site address, in SAWLA Interlab's case, ping www.lab.com

If the system is reachable, the ping command will return a narrative indicating how long it took to send and retrieve test packages of data

DNS failure

If the domain name (DNS) look-up is failing, the narrative will say 'Unable to resolve host name' or something similar

Test if this is true with another familiar site, say ping www.google.com

If the error message persists, please contact the your Internet Service provider and explain the the test you have just done and that you suspect the domain name service (DNS) fails

Broken Network

If the ping command returns and error message 'Request timed out', there might be a broken link in your internet connection to the system

Then run the trace route command in the  DOS window, type tracert and the system or site address, in SAWLA Interlab's case, tracert www.lab.com

The command will return a narrative listing all the links to the system and which one cannot be used because it is down

Please contact the your Internet Service provider and explain the the test you have just done and that you suspect network failure