What must be done before installing an OS from an installation CD?

Before installing an operating system from an installation CD, configuring the BIOS setup is essential. The BIOS (Basic Input/Output System) controls the hardware initialization process and the boot sequence of the computer. To ensure that the installation CD can be read correctly, the BIOS needs to be set to prioritize the CD/DVD drive in the boot order. This configuration ensures that when the system starts, it looks for bootable media in the correct order, allowing the OS installation to commence from the CD.

While checking for existing viruses or connecting to the internet may be beneficial to maintain system integrity or obtain updates, these actions can occur after the OS installation. Downloading necessary updates is typically performed after the OS has been installed, when the system is operational and connected to the internet. Thus, configuring the BIOS is the crucial step that directly affects the ability to boot from the installation medium.