CompTIA Linux+ Practice Questions: Troubleshooting Domain

Published: September 21, 2025 | 20 min read

Test your CompTIA Linux+ knowledge with 10 practice questions from the Troubleshooting domain. Includes detailed explanations and answers.

CompTIA Linux+ Practice Questions

Master the Troubleshooting Domain

Test your knowledge in the Troubleshooting domain with these 10 practice questions. Each question is designed to help you prepare for the CompTIA Linux+ certification exam with detailed explanations to reinforce your learning.

Question 1

A cloud-based CentOS server is experiencing intermittent connectivity issues. Which command would help diagnose potential network problems?

A) ping -c 4 google.com

B) traceroute google.com

C) ifconfig eth0

D) netstat -rn

Show Answer & Explanation

Correct Answer: B

Explanation: The 'traceroute' command helps diagnose network path issues by showing the route packets take to a destination and where delays or failures occur. 'Ping' (A) tests connectivity but not the path. 'Ifconfig' (C) displays network interface configuration, not connectivity issues. 'Netstat -rn' (D) shows the routing table, which is useful but less direct for diagnosing intermittent connectivity.

Question 2

You are troubleshooting a Linux server that is running slowly. Which of the following commands would help you identify CPU-intensive processes?

A) top

B) free

C) du

D) ifconfig

Show Answer & Explanation

Correct Answer: A

Explanation: The 'top' command provides a real-time view of system processes, including CPU and memory usage, which can help identify CPU-intensive processes. 'free' shows memory usage, 'du' is for disk usage, and 'ifconfig' is used for network interface configuration.

Question 3

A user reports that they cannot SSH into a CentOS server. Which of the following could be the cause?

A) The SSH service is not running.

B) The server's firewall is allowing traffic on port 22.

C) The user's password is correct.

D) The server is connected to the network.

Show Answer & Explanation

Correct Answer: A

Explanation: If the SSH service is not running, users will not be able to connect to the server via SSH. Options B, C, and D describe conditions that would support successful SSH access, not prevent it.

Question 4

Which command can be used to check the current system load and identify processes consuming high CPU resources on an Ubuntu server?

A) ps aux

B) top

C) df -h

D) free -m

Show Answer & Explanation

Correct Answer: B

Explanation: The 'top' command provides a dynamic, real-time view of the running system, including system load and CPU usage by processes. Option A, 'ps aux', lists processes but does not provide real-time CPU usage. Option C, 'df -h', shows disk space usage. Option D, 'free -m', displays memory usage.

Question 5

A containerized application is not starting in a Kubernetes cluster. Which command can you use to get detailed logs of the failed pod?

A) kubectl get pods

B) kubectl describe pod

C) kubectl logs

D) kubectl exec -it -- /bin/sh

Show Answer & Explanation

Correct Answer: B

Explanation: The 'kubectl describe pod ' command provides detailed information about the pod, including events and error messages that can help diagnose why the pod is not starting. 'kubectl get pods' lists pods, 'kubectl logs' shows application logs, and 'kubectl exec' provides shell access to a running container.

Question 6

Which command would you use to check the current status of the Apache service on a CentOS server?

A) systemctl status apache2

B) service apache2 status

C) systemctl status httpd

D) service httpd status

Show Answer & Explanation

Correct Answer: C

Explanation: On CentOS, the Apache service is typically referred to as 'httpd'. The 'systemctl status httpd' command is used to check the current status of the Apache service. Option A is incorrect because 'apache2' is the service name used in Debian-based distributions like Ubuntu. Option B is incorrect for the same reason as A, and it uses the older 'service' command. Option D uses the correct service name but the older 'service' command, which is less commonly used in newer systems where 'systemctl' is preferred.

Question 7

A user cannot connect to a database running in a cloud environment. Which command would help verify if the database port is accessible?

A) curl

B) netcat (nc)

C) traceroute

D) dig

Show Answer & Explanation

Correct Answer: B

Explanation: The 'netcat' or 'nc' command can be used to check if a specific port is open by attempting to establish a connection, which is useful for verifying database port accessibility. Option A, 'curl', is used for transferring data with URLs. Option C, 'traceroute', is used to trace the path packets take to a destination. Option D, 'dig', is used for DNS queries.

Question 8

A cloud-based Ubuntu server is not responding to HTTP requests. You suspect the firewall is blocking traffic. Which command would you use to check the firewall status?

A) ufw status

B) iptables -L

C) firewall-cmd --state

D) netstat -tuln

Show Answer & Explanation

Correct Answer: A

Explanation: The 'ufw status' command is used on Ubuntu systems to check the status of the uncomplicated firewall (UFW). Option B is used to list iptables rules, which is more complex and not specific to UFW. Option C is used with firewalld, not UFW. Option D lists active network connections but does not provide firewall status.

Question 9

A user reports that they cannot connect to a PostgreSQL database on a CentOS server. Which configuration file should be checked first?

A) /etc/postgresql/pg_hba.conf

B) /etc/postgresql/postgresql.conf

C) /var/lib/pgsql/data/pg_hba.conf

D) /var/lib/pgsql/data/postgresql.conf

Show Answer & Explanation

Correct Answer: C

Explanation: On CentOS, the 'pg_hba.conf' file located in '/var/lib/pgsql/data/' is responsible for client authentication settings and should be checked first for connection issues. Option A is a common path for Debian-based systems, and Options B and D relate to general database configuration, not specifically client authentication.

Question 10

A user cannot access a web application hosted in a container on an Ubuntu server. The container is running, and the web server inside the container is listening on port 8080. What should you check next?

A) Container's network configuration

B) Server's firewall settings

C) DNS resolution for the server

D) Application logs inside the container

Show Answer & Explanation

Correct Answer: B

Explanation: The server's firewall settings may be blocking access to port 8080, preventing external access to the web application. The container's network configuration (A) is less likely to be the issue if the container is running and the service is listening. DNS resolution (C) would affect name resolution, not port access. Application logs (D) would be useful if the application itself was malfunctioning but not if it's a network access issue.

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About CompTIA Linux+ Certification

The CompTIA Linux+ certification validates your expertise in troubleshooting and other critical domains. Our comprehensive practice questions are carefully crafted to mirror the actual exam experience and help you identify knowledge gaps before test day.