Final answer:
A system can be booted using a CD-ROM/DVD, a network adapter through PXE, or a USB drive with a bootable partition. An internet connection alone is not a bootable option.
Step-by-step explanation:
To boot a system means to start it up or initiate its operating system. The devices you can use to boot a system are:
- CD-ROM/DVD: An optical drive can be used to boot a system if it contains a bootable CD or DVD with an operating system installation or live system environment.
- Network adapter: Using a process known as PXE (Preboot Execution Environment), a computer can be booted remotely from a server over a network.
- USB drive: If it has a bootable partition, a USB drive can initiate the startup sequence of a computer.
However, an internet connection alone cannot be used to boot a system as it does not directly interface with the computer's hardware to initiate the boot process.