What happens when a computer is offline and a WebClient makes a request?

What happens when I make a request with a WebClient object when the computer is offline? Is there a way to detect that beforehand. or should I be handling some so开发者_Python百科rt of exception?

A WebException will be thrown. http://msdn.microsoft.com/en-us/library/system.net.webexception(v=vs.80).aspx