Definition of Active Setup in The Network Encyclopedia.
What is Active Setup?
Active Setup is a Microsoft ActiveX engine that can be used to interactively download and install software over the Internet using a standard Web browser such as Microsoft Internet Explorer.
How does Active Setup Work?
Active Setup makes use of the fact that source files of the application to be installed are partitioned into segments, the traditional ACME setup cabinet files (*.cab files).
Active Setup begins by downloading a small, self-extracting setup package to the browser client. This file also collects information about the client’s computer to help determine which components already exist on the system and whether the desired application is compatible with the system’s configuration.
The user specifies a location from which to download the desired application and the types of components to be installed. The application’s *.cab files are then downloaded as needed, after which Active Setup is completed and normal ACME setup can continue.

If Download is interrupted
One advantage of Active Setup is that if the download is interrupted, it can be resumed at the interruption point rather than at the beginning.