Identifying can be tricky, but the two general classes are installations having InstallScript-based dialog boxes and those with Windows Installer-based dialog boxes.
For installations using InstallScript-based dialog boxes (built with what are called InstallScript projects and InstallScript MSI projects), the big idea is first to generate a response file by running setup.exe with the /r switch (and possibly /f1 to specify where the response file goes); this creates a file that describes what you entered in the installation dialog boxes. You then run the installer on other systems using that response file by running setup.exe with the /s switch (and possibly /f1 to specify where the response file is and what it's called).
For Windows Installer installations, a command like setup.exe /s /V"/qn" should do the trick. If you want to change installation settings, you pass the values of properties on the command line.
For more information, please see the "silent installations" topic in the InstallShield help at http://helpnet.acresso.com.
