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.
A system administrator needs to restrict SSH access to a Linux server to only users in the 'sshusers' group. Which configuration change achieves this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add 'AllowGroups sshusers' to /etc/ssh/sshd_config
Option C is correct because the 'AllowGroups' directive in /etc/ssh/sshd_config restricts SSH access to only users who are members of the specified group. When set to 'AllowGroups sshusers', only users belonging to the 'sshusers' group will be permitted to log in via SSH, effectively blocking all others. This is the standard method for group-based access control in 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.
✗
Add 'DenyUsers *' to /etc/ssh/sshd_config
Why it's wrong here
DenyUsers * would block all users, not restrict to a group.
✗
Set 'PermitRootLogin no' in /etc/ssh/sshd_config
Why it's wrong here
This only disables root login, not group-based access.
✓
Add 'AllowGroups sshusers' to /etc/ssh/sshd_config
Why this is correct
AllowGroups restricts SSH access to members of the specified group.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add 'AllowUsers sshusers' to /etc/ssh/sshd_config
Why it's wrong here
AllowUsers expects usernames, not group names.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between 'AllowUsers' (which expects usernames) and 'AllowGroups' (which expects group names), leading candidates to incorrectly choose 'AllowUsers sshusers' thinking it applies to the group rather than a user literal.
Detailed technical explanation
How to think about this question
The 'AllowGroups' directive in sshd_config uses the system's group membership (via /etc/group or LDAP) to filter authentication at the PAM or sshd level before password or key verification. This is more efficient than 'AllowUsers' for large environments because group membership can be managed centrally, and it works seamlessly with both password and public key authentication. A subtle behavior is that 'AllowGroups' and 'DenyGroups' can be combined, but 'AllowGroups' takes precedence over 'DenyGroups' if both are specified.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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: Add 'AllowGroups sshusers' to /etc/ssh/sshd_config — Option C is correct because the 'AllowGroups' directive in /etc/ssh/sshd_config restricts SSH access to only users who are members of the specified group. When set to 'AllowGroups sshusers', only users belonging to the 'sshusers' group will be permitted to log in via SSH, effectively blocking all others. This is the standard method for group-based access control in 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This XK0-005 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the XK0-005 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.