1Z0-106 practice question 9 of 15

As root you configured a file system using AutoFS with default settings. In the first session, you changed to a directory under AutoFS control. In a second session, you changed to /etc. Now the idle time for the session expires. Which two statements are true about the status of the file system mounted in the first session?

Full set: 60 questions

Answer options

A: It remains mounted as long as the system is running.

B: It remains mounted until you log out from the first session. Correct answer

C: It was unmounted from the first session when the timer expired.

D: It was unmounted when the second session began.

E: It remains mounted until you switch to a directory outside the current mount point. Correct answer

Correct Answer:

B. It remains mounted until you log out from the first session.; E. It remains mounted until you switch to a directory outside the current mount point.

Explanation

The AutoFS service automatically mounts a filesystem upon access and is designed to unmount it after a period of inactivity (the idle timeout). In the described scenario, the first session changes its current working directory (CWD) into the AutoFS-managed directory, which triggers the mount. Because the shell process in the first session maintains its CWD within this mounted filesystem, the filesystem is considered "in use" or "busy". The automount daemon will not unmount a busy filesystem, even after the idle timeout expires. The filesystem will only be unmounted after it is no longer busy and the subsequent idle timeout period passes. The "busy" state is released when the process (the shell) either changes its CWD to a location outside the mount point or terminates (e.g., by logging out).

Why Incorrect

A. AutoFS is specifically designed to unmount idle filesystems to conserve resources; they do not persist for the entire system uptime unless constantly in use.
C. The filesystem cannot be unmounted when the timer expires because the shell's CWD in the first session keeps the resource busy.
D. Actions in a second, unrelated session and directory (/etc) have no impact on the mount status of the filesystem used by the first session.

References

1. Oracle Linux 8 Documentation

Managing Storage Devices

Chapter 20. Automounting File Systems with AutoFS: The documentation explains the timeout mechanism. While it doesn't explicitly detail the "busy" state in the introductory sections

the underlying umount behavior it relies on prevents unmounting a filesystem that is in use (e.g.

by a process's CWD). The core principle is that unmounting only occurs on idle filesystems.

Reference: Oracle® Linux 8: Managing Storage Devices

Section 20.1

"About AutoFS".

2. autofs(5) Linux man page: This primary source document describes the behavior of the automounter. A key operational principle is that busy filesystems are not unmounted.

Quote: "The automounter will not unmount a filesystem that is in use." A shell's CWD within a mount point defines it as "in use".

3. University of Washington

CSE 451

Introduction to Operating Systems Courseware: Academic materials on Linux/UNIX filesystems corroborate this behavior.

Reference: Lecture notes on Network File Systems often describe AutoFS behavior

stating: "Autofs will not unmount a filesystem if any process has it as its current working directory

or has any open file in it." This directly supports why the filesystem remains mounted in the scenario.

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