Apple Certified Support Professional (ACSP) Practice Exam

Before performing a clean installation of macOS (formerly known as OS X), it is essential to manually erase the system disk using Disk Utility. This step ensures that any existing data, previous installations, or corrupt files on the disk are completely removed. A clean installation creates a fresh environment, allowing the new operating system to be installed without any remnants of the old system.

Erasing the disk prepares it by formatting it properly for macOS installation, which typically uses the APFS or Mac OS Extended file systems. This step is crucial to prevent conflicts that might arise from leftover data or software on the disk that could lead to functionality issues with the newly installed operating system.

While it could be beneficial to have the system updated, connected to a network, or formatted in certain ways, none of these are prerequisites for performing the clean installation compared to the necessity of erasing the disk appropriately.