The third type of error is a ``connection refused'' error. This will occur when you are able to connect to a remote host and it is up and running but you are not allowed to use it for some reason. Those reasons include the fact that you are not authorized (check to make sure you typed your login name and password correctly), or in the case of anonymous FTP servers there might be an upper limit on the number of guest users at any one time or the hours for public access might be restricted. In these cases the error message is usually accompanied by an explanation of why you have not been granted access.
(See exercises 6, 6, 6, and 6.)