What boot method should be used for a network-based Windows upgrade?

Using PXE, or Preboot Execution Environment, is the appropriate boot method for a network-based Windows upgrade. PXE allows a computer to boot from an image located on a server in the network instead of from local storage devices like hard drives or USB drives. This is particularly useful in environments where multiple machines need to be upgraded or installed simultaneously, as it simplifies deployment by centralizing the installation files on a server.

When a device is configured to boot via PXE, it connects to the network, requests a boot image, and downloads it to perform the installation. This method is efficient, especially in corporate settings, where IT departments can manage upgrades and installations over the network.

Other options like SSD, optical drives, or flash drives involve local storage and require physical media or connections to install an operating system, which is not an efficient solution for network-based upgrades.