Which file is checked to determine what partitions should be automatically mounted?

The file that is checked to determine what partitions should be automatically mounted is the /etc/fstab file. This configuration file contains information about all available disk partitions and their mount points, along with other options. Each line in the /etc/fstab file corresponds to a different filesystem, specifying where the filesystem should be mounted, which device it corresponds to, the type of filesystem, and any options related to its mounting behavior.

When the system boots or when a command is issued to mount filesystems, the system reads this file to know what to mount automatically and how. It is an essential part of managing filesystems in a Linux environment, ensuring that necessary partitions are available for use as soon as the system starts up.

The other files listed serve different purposes: /etc/hosts is used for hostname resolution, /etc/passwd stores user account information, and /etc/init.d contains scripts for starting and stopping services during system initialization.