Top 20+ Must‑Know Docker, Nginx, Shell & Jenkins Interview Questions

In a competitive job market, mastering core skills and staying updated with cutting‑edge technologies is essential. This guide compiles over 20 high‑frequency technical interview questions covering Docker, Nginx, Shell scripting, and Jenkins to help candidates prepare for the recruitment season.

Docker Interview Questions

1. What is Docker? 2. What is a Docker image? 3. What is a Docker container? 4. How many states can a Docker container have? 5. What is the most common instruction specified in a Dockerfile? 6. What is the difference between the COPY and ADD commands in a Dockerfile? 7. Common Docker commands? 8. Commands for copying data between host and container? 9. Command to start an Nginx container with random port mapping and mount a local directory to the container's HTML directory? 10. Explain the ONBUILD instruction in a Dockerfile. 11. What is Docker Swarm? 12. How to monitor Docker in production? 13. How does Docker run containers on non‑Linux systems? 14. How to batch clean temporary image files? 15. How to view environment variables supported by an image? 16. Where are local image files stored? 17. Principles to follow when building a Docker image? 18. If a container exits and is not shown by docker ps , is the data lost? 19. How to stop all running containers? 20. How to clean up stopped containers in bulk? 21. How to temporarily exit an interactive container terminal without terminating it? 22. How to view output and log information of background‑running application containers? 23. Meaning of the error "Error: No public port '80' published for ..." when using docker port ? 24. Can multiple application processes run in a single container? 25. How to control a container's share of system resources (CPU, memory)? 26. Relationship between Repository, Registry, and Index? 27. Where are Docker configuration files and how to modify them? 28. How to change Docker's default storage settings? 29. Differences between Docker and Vagrant? 30. Differences between Docker and LXC (Linux Container)? ......

Nginx Interview Questions

1. Explain what Nginx is. 2. List some features of Nginx. 3. Compare Nginx with Apache. 4. Explain how Nginx handles HTTP requests. 5. How to block requests using an undefined server name in Nginx? 6. Advantages of using a reverse proxy server. 7. Best use cases for an Nginx server. 8. Explain the roles of Master and Worker processes in Nginx. 9. How to start Nginx on a non‑standard port? 10. Can Nginx error responses be replaced with 502/503 errors? 11. How to preserve double slashes in a URL? 12. Purpose of the ngx_http_upstream_module . 13. What is the C10K problem? 14. Functions of the stub_status and sub_filter directives. 15. Does Nginx support compressing requests to upstream servers? 16. How to obtain the current time in Nginx? 17. Purpose of the -s flag in Nginx. 18. How to add modules to Nginx? 19. Why use Nginx? 20. Why is Nginx performance so high? 21. How does Nginx process requests? 22. Difference between forward and reverse proxy. 23. Advantages of a reverse proxy server. 24. Pros and cons of Nginx. 25. Typical application scenarios for Nginx. 26. Nginx directory structure. 27. Key directives and modules in nginx.conf . 28. Handling of static resources in Nginx. 29. Solving front‑end cross‑origin issues with Nginx. 30. Configuring virtual hosts in Nginx. ......

Shell Script Interview Questions

1. What is a shell script and is it necessary? 2. What is the default login shell and how to change a user's login shell? 3. What types of variables can be used in shell scripts? 4. How to redirect both standard output and error output to the same location? 5. How to nest if statements in a shell script? 6. Purpose of the $? variable? 7. How to compare two numbers in a shell script? 8. Function of the break command? 9. Function of the continue command? 10. Syntax of the case statement? 11. Syntax of the while loop? 12. How to make a script executable? 13. Purpose of #!/bin/bash ? 14. Syntax of the for loop? 15. How to debug a shell script? 16. How to compare strings in a shell script? 17. Special variables in Bourne shell (bash)? 18. How to test a file in a shell script? 19. How to write comments in a shell script? 20. How to read input from the terminal? 21. How to unset a variable or its value? 22. How to perform arithmetic operations? 23. Basic format of a do‑while loop? 24. How to define a function in a shell script? 25. How to generate a random string or number? 26. Define a function that outputs colored strings. 27. Batch create users. 28. Check if a package is installed. 29. Check service status. 30. Check host liveness. ......

Jenkins Interview Questions

1. What is Jenkins? 2. Why use Jenkins? 3. What is CI/CD? 4. Common CI tools? 5. What is a Jenkins pipeline? 6. Why use pipelines in Jenkins? 7. What is a Jenkinsfile and why use it? 8. What is Blue Ocean? 9. How to backup and copy files in Jenkins? 10. Advantages of Jenkins. 11. Two main components integrated by Jenkins. 12. Useful Jenkins plugins. 13. Which plugins have you used? 14. How to backup and restore Jenkins? 15. What are Maven and Jenkins? 16. Difference between Hudson and Jenkins. 17. What is continuous integration in Jenkins? 18. Why use Jenkins with Selenium? 19. What is a CI/CD pipeline? 20. What is a build pipeline in Jenkins? 21. What is a Jenkins Pipeline? 22. What is DSL Jenkins? 23. Difference between continuous integration and deployment. 24. Tools for configuration management? 25. Difference between Maven, Ant, and Jenkins. 26. Which SCM tools does Jenkins support? 27. How to schedule builds in Jenkins? 28. Why use pipelines in Jenkins? 29. What is a Jenkinsfile? 30. How to create a multibranch pipeline in Jenkins? ......