This XK0-005 practice question tests your understanding of troubleshooting. 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.
A user is able to ping the Linux server but cannot connect via SSH. The SSH service is running and listening. Which configuration file should the administrator review FIRST?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
/etc/pam.d/login
Why wrong: PAM configuration for login, not SSH.
/etc/ssh/sshd_config
Contains authentication methods and other critical settings.
/etc/nsswitch.conf
Why wrong: Controls name resolution order, not SSH authentication.
/etc/hosts.allow
Why wrong: Used by tcpwrappers, less common for SSH issues.
Answer choices
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
The correct answer is B because the SSH service is running and listening, but the user cannot connect. This points to a configuration issue within the SSH daemon itself. The `/etc/ssh/sshd_config` file controls SSH server settings such as allowed authentication methods, port numbers, and user access restrictions (e.g., `AllowUsers`, `DenyUsers`, `PermitRootLogin`). Reviewing this file first is the logical step to identify why connections are being rejected despite the service being active.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
/etc/pam.d/login
Why it's wrong here
PAM configuration for login, not SSH.
/etc/ssh/sshd_config
Why this is correct
Contains authentication methods and other critical settings.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
/etc/nsswitch.conf
Why it's wrong here
Controls name resolution order, not SSH authentication.
/etc/hosts.allow
Why it's wrong here
Used by tcpwrappers, less common for SSH issues.
Common exam traps
The trap here is that candidates often jump to `/etc/hosts.allow` or PAM files because they associate 'cannot connect' with access control or authentication, but the question specifies the service is running and listening, which narrows the issue to SSH-specific configuration in `sshd_config`.
Detailed technical explanation
The SSH daemon (sshd) reads its configuration from `/etc/ssh/sshd_config` at startup and on reload via SIGHUP. Common misconfigurations include setting `PermitRootLogin no`, restricting `AllowUsers` or `AllowGroups`, or binding to a non-standard IP address. A subtle behavior is that `sshd` may ignore `hosts.allow`/`hosts.deny` entirely unless the `--with-libwrap` compile flag was used, making `/etc/hosts.allow` an irrelevant first check in most modern Linux distributions.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Troubleshooting — study guide chapter
Learn the concepts, then practise the questions
Troubleshooting practice questions
Targeted practice on this topic area only
All XK0-005 questions
510 questions across all exam domains
CompTIA Linux+ XK0-005 study guide
Full concept coverage aligned to exam objectives
XK0-005 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise XK0-005 questions linked to Security.
Practise XK0-005 questions linked to Troubleshooting.
Practise XK0-005 questions linked to Scripting, Containers and Automation.
Practise XK0-005 questions linked to System Management.
Practise XK0-005 questions linked to XK0-005 fundamentals.
Practise XK0-005 questions linked to XK0-005 scenario.
Practise XK0-005 questions linked to XK0-005 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
The correct answer is: /etc/ssh/sshd_config — The correct answer is B because the SSH service is running and listening, but the user cannot connect. This points to a configuration issue within the SSH daemon itself. The `/etc/ssh/sshd_config` file controls SSH server settings such as allowed authentication methods, port numbers, and user access restrictions (e.g., `AllowUsers`, `DenyUsers`, `PermitRootLogin`). Reviewing this file first is the logical step to identify why connections are being rejected despite the service being active.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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 →
Last reviewed: Jun 25, 2026
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.