Distributed COM (DCOM) is a Microsoft technology that provides Windows applications with the ability to connect from one computer to another on a LAN, a WAN, or an Internet connection. For example, DCOM allows the OPC client application to communicate from one computer to the OPC server on another computer.
DCOM can be quite potent and enable many interesting applications. However it is important to understand the details to ensure OPC works properly using DCOM. Please refer to your operating system under the DCOM Config section in this website to best set up DCOM for your OPC use.