When connected to a host system, the title bar shows the method of connection to the host. You can easily tell if ZTERM 2000 is connected to the host by looking at the title bar.
ZTERM 2000 is disconnected:
ZTERM 2000 is connected:
Note the method used to connect is shown in the title bar -- in this an IP address for use with telnet, but also shows the COM port or hostname.