title: non-routable IP address
body: <p>I know that 127.0.0.1 is by convention the loopback address and that there are various address ranges which are reserved for local use.</p>
  
  <p>Is there an IP address that is reserved never to be assigned?</p>
  
  <p>I would like to test that something works when an IP address can't be found, I could just use a local address which isn't used but thought that there may be an address which is reserved for such use.</p>