In server-based interface your application connects to the DLN server by TCP/IP and the server routes your requests to the appropriate adapter.
Benefits of the server-based interface:
Several applications can communicate with the same adapter simultaneously.
The DLN-series adapter (together with the DLN server) can be connected to a remote PC (even if one is located at another part of the world). All the communication is done through TCP/IP.
Single application can manage multiple adapters that are connected to different computers.