What defines how a network workstation can boot and load an operating system from a central network server?

The correct choice focuses on PXE, which stands for Preboot Execution Environment. PXE is a technology that allows a networked computer (client) to boot operating system software from a server on the network, rather than from a local storage device such as a hard drive or USB stick.

When a workstation is set to boot via PXE, it sends a request over the network to find a PXE server. The server then provides the necessary boot loader and operating system image across the network, allowing the workstation to load and execute the operating system without needing any prior installation on a local disk. This process is especially useful in environments where many computers need to be set up with the same configuration quickly, such as in corporate or educational settings.

Other choices, while related to network functionality, do not serve the same purpose. DHCP, for example, is used for dynamically assigning IP addresses to devices on a network, providing them with the necessary configuration to connect to the network but not specifically handling the booting process. FTP and HTTP are file transfer and web protocols, respectively, that allow for the transmission of files over a network, but they are not designed for booting an operating system. PXE is specifically tailored to facilitate the network booting process