This XK0-005 practice question tests your understanding of security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
An administrator needs to ensure that the SSH service only allows key-based authentication and disables password authentication. Which configuration file and directive should be modified?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
/etc/ssh/sshd_config; PasswordAuthentication no
Option D is correct because the SSH server configuration file is /etc/ssh/sshd_config, and setting 'PasswordAuthentication no' disables password-based logins, forcing key-based authentication. This directive must be set on the server side (sshd_config), not the client side (ssh_config), to enforce the policy for all incoming SSH connections.
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.
✗
/etc/ssh/sshd_config; PasswordAuthentication yes
Why it's wrong here
This would enable password authentication, the opposite of what is needed.
✗
/etc/ssh/sshd_config; PubkeyAuthentication no
Why it's wrong here
This disables key-based authentication, which is not desired.
✗
/etc/ssh/ssh_config; PasswordAuthentication no
Why it's wrong here
ssh_config is for client connections, not the server.
✓
/etc/ssh/sshd_config; PasswordAuthentication no
Why this is correct
Correct file and directive to disable password authentication.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing the client configuration file (/etc/ssh/ssh_config) with the server configuration file (/etc/ssh/sshd_config), leading candidates to select option C, which would have no effect on the SSH server's authentication behavior.
Detailed technical explanation
How to think about this question
The SSH server (sshd) reads /etc/ssh/sshd_config at startup; changes require a restart or SIGHUP signal to take effect. When PasswordAuthentication is set to 'no', the server rejects any password-based login attempt, even if the client offers a password, and only accepts authentication methods like publickey, gssapi-with-mic, or keyboard-interactive (if not explicitly disabled). In practice, administrators often combine this with 'PubkeyAuthentication yes' (the default) and 'ChallengeResponseAuthentication no' to fully lock down password-based access.
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 practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: /etc/ssh/sshd_config; PasswordAuthentication no — Option D is correct because the SSH server configuration file is /etc/ssh/sshd_config, and setting 'PasswordAuthentication no' disables password-based logins, forcing key-based authentication. This directive must be set on the server side (sshd_config), not the client side (ssh_config), to enforce the policy for all incoming SSH connections.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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