Which of the following file systems cannot be mounted by using the mount command?

• A. Ext4
• B. Swap
• C. Ntfs
• D. Vfat

Answer: (B)

Mounting is the process of attaching a filesystem to a directory (a mount point) so the operating system can access its files. Swap space, however, is not a filesystem; it’s memory the kernel uses for paging. Because there’s no filesystem structure to mount, the mount command cannot mount swap. To enable or disable swap you use swapon and swapoff on a swap device or swap file. In contrast, Ext4, Ntfs, and Vfat are real filesystems with metadata and data blocks that can be mounted to access files, which is why they are valid targets for the mount command.