title: Does tcp/ip protocol explained when connection will time out or be refused?
body: <p>While a tcp client is connecting to a tcp server, and at same time the Listening port at server side hasn't been established. At this time will the tcp client report connection refused exception or connection time out exception ?</p>
  
  <p>At first I think a connection refused exception will be reported by tcp/ip, because the server could check if the LISTEN port( which is connected by client) is exist. But actually a connection time out instead.</p>
  
  <p>I am wondering if tcp/ip protocol has explained such a situation?</p>