The next type of error may or may not be accompanied by an error message. It occurs when the host name is valid but the connection is still not being made. If you wait long enough, the application might quit with an error message like ``connection timed out'' or ``route to the remote host is not available." There are several reasons for this type of message: the remote host might be down for repairs, there might be network connection problems somewhere between your system and the remote host, or your system or the host might be behind a firewall . It may seem strange that hosts that are not directly connected to the Internet will have their names and addresses published in name server tables, but there are many reasons why the names might be there. Those hosts can still use TCP/IP applications within their local networks, and the local name servers might include those names when queried by global name servers, or the names might have been published in global name servers before the systems were placed behind a firewall.