The answer is to check the SSH daemon configuration file, firewall rules, and service status. The primary configuration file for the OpenSSH server, /etc/ssh/sshd_config, controls critical settings like the listening port, permitted authentication methods, and whether root login is allowed; a syntax error or a misconfigured directive here will silently prevent connections. On the CompTIA Linux+ XK0-005 exam, this question tests your systematic approach to service troubleshooting, often hiding traps where a candidate jumps to restarting the service without verifying the config file first. When you cannot SSH into a Linux server, always start by checking the sshd_config for errors, then confirm the sshd service is running with systemctl status sshd, and finally inspect firewall rules using iptables -L or ufw status to ensure port 22 is open. Remember the mnemonic “CSF” — Config, Service, Firewall — to lock in the correct order of attack.
XK0-005 Troubleshooting Practice Question
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 Linux server is not accepting SSH connections. The administrator wants to troubleshoot the issue. Which THREE actions should be taken?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check /etc/ssh/sshd_config for configuration errors
B is correct because /etc/ssh/sshd_config is the primary configuration file for the OpenSSH server. Syntax errors, incorrect directives (e.g., PermitRootLogin no, Port 22 commented out), or misconfigured authentication settings can prevent SSH from accepting connections. Checking this file is a fundamental step in troubleshooting SSH issues.
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.
✗
Reboot the server
Why it's wrong here
Last resort; not a troubleshooting step.
✓
Check /etc/ssh/sshd_config for configuration errors
Why this is correct
Correct: Misconfiguration can prevent connections.
Related concept
Read the scenario before looking for a memorised answer.
✓
Check if sshd service is running (systemctl status sshd)
Why this is correct
Correct: First step to ensure service is active.
Related concept
Read the scenario before looking for a memorised answer.
✗
Reinstall the SSH package (apt reinstall openssh-server)
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that reinstalling a package or rebooting is a valid first troubleshooting step, when in reality, checking configuration files, service status, and firewall rules are the precise, targeted actions required.
Detailed technical explanation
How to think about this question
The sshd daemon reads its configuration at startup; a syntax error in sshd_config can cause the service to fail to start or ignore certain directives. The systemctl status sshd command shows the service's active state, recent logs, and exit codes (e.g., 'failed' with a specific error). Firewall rules (iptables -L or ufw status) can block port 22 (TCP) even if sshd is running, so checking both the service and firewall is essential for a complete diagnosis.
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.
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check /etc/ssh/sshd_config for configuration errors — B is correct because /etc/ssh/sshd_config is the primary configuration file for the OpenSSH server. Syntax errors, incorrect directives (e.g., PermitRootLogin no, Port 22 commented out), or misconfigured authentication settings can prevent SSH from accepting connections. Checking this file is a fundamental step in troubleshooting SSH issues.
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
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
medium
A./etc/pam.d/login
✓ B./etc/ssh/sshd_config
C./etc/nsswitch.conf
D./etc/hosts.allow
Why B: 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.
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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
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