The answer is that the sshd service failure is most likely caused by a missing privilege separation directory, specifically /var/empty/sshd. This directory is critical because it serves as a chroot jail for the unprivileged sshd process after authentication, allowing the service to drop root privileges and operate in a restricted environment for security. Without it, sshd cannot complete its privilege separation routine, leading to an immediate startup failure with the exact error message you would see in logs or systemd status output. On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding of OpenSSH security hardening and common post-installation pitfalls; a common trap is assuming the issue is a firewall or key permission problem when the error explicitly names the missing directory. A quick memory tip: think of /var/empty/sshd as the “empty room” where sshd safely locks itself away after letting you in—if the room is gone, the door stays shut.
XK0-005 System Management Practice Question
This XK0-005 practice question tests your understanding of system management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
$ systemctl status sshd
● sshd.service - OpenSSH server daemon
Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Mon 2023-06-12 09:15:22 UTC; 5min ago
Docs: man:sshd(8)
man:sshd_config(5)
Process: 1234 ExecStart=/usr/sbin/sshd -D $OPTIONS (code=exited, status=255)
Main PID: 1234 (code=exited, status=255)
Status: "Failed to start sshd"
Jun 12 09:15:22 server sshd[1234]: fatal: Missing privilege separation directory: /var/empty/sshd
Based on the exhibit, what is the most likely cause of the sshd service failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The privilege separation directory /var/empty/sshd does not exist.
The error message 'Privilege separation directory /var/empty/sshd does not exist' directly indicates that the required chroot directory for the unprivileged sshd process is missing. Without this directory, sshd cannot drop privileges after authentication, causing it to fail on startup. This is a common issue after a partial installation or cleanup of OpenSSH.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The SSH configuration file has a syntax error.
Why it's wrong here
No syntax error is indicated; the error is about a missing directory.
✓
The privilege separation directory /var/empty/sshd does not exist.
Why this is correct
The error message directly states this directory is missing.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The sshd PID file cannot be written.
Why it's wrong here
No PID file error is shown; the failure is due to missing directory.
✗
The SSH port is already in use by another service.
Why it's wrong here
No port conflict is mentioned in the logs.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the specific error message 'Privilege separation directory /var/empty/sshd does not exist' to trap candidates who assume the failure is due to a configuration syntax error or port conflict, rather than recognizing the missing chroot directory as a distinct startup prerequisite.
Trap categories for this question
Command / output trap
No PID file error is shown; the failure is due to missing directory.
Detailed technical explanation
How to think about this question
The privilege separation mechanism in OpenSSH (introduced in OpenSSH 3.2.2) creates an unprivileged child process that handles network communication, while the privileged monitor process remains in a restricted chroot jail at /var/empty/sshd. This directory must be owned by root and have permissions 755; if it is missing, sshd will refuse to start to prevent running without privilege separation, which is a security requirement. In some distributions, this directory is created by the package manager, but manual compilation or cleanup can omit it.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
System Management — This question tests System Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The privilege separation directory /var/empty/sshd does not exist. — The error message 'Privilege separation directory /var/empty/sshd does not exist' directly indicates that the required chroot directory for the unprivileged sshd process is missing. Without this directory, sshd cannot drop privileges after authentication, causing it to fail on startup. This is a common issue after a partial installation or cleanup of OpenSSH.
What should I do if I get this XK0-005 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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