Final answer:
A directory listing index $I30 is a component of the NTFS file system, responsible for storing and organizing directory data for a folder on a disk.
Step-by-step explanation:
A directory listing index $I30 is a component of the file system in the NTFS file system used by Windows operating systems.
The $I30 index is responsible for storing and organizing the directory data for a particular folder on a disk. It keeps track of the file and folder names, as well as their metadata such as size, timestamps, and permissions.
This index is crucial for efficient file system operations, as it allows the operating system to quickly locate and access the files and folders stored on a disk.