Docker & Kubernetes · Complete Question Bank

All Docker & Kubernetes Interview Questions

Practice the complete collection of Docker & Kubernetes interview questions including theory, coding, MCQs and real interview problems.

Total Questions: 104Topics: 42Complete interview preparation

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All Docker & Kubernetes Interview Questions (104)

Scroll through every important Docker & Kubernetes question asked in real interviews. Includes MCQs, subjective questions, and coding prompts.

1. What is the primary purpose of using Docker?

Difficulty: EasyType: MCQTopic: Docker Basics

To create full virtual machines with separate kernels
To package applications and their dependencies into portable containers
To replace an operating system entirely
To build front-end user interfaces

Docker is a containerisation platform that lets you bundle an application plus its dependencies into a lightweight, portable unit. This ensures consistent behaviour across different environments. It is widely used to solve the "works on my machine" problem by packaging code and dependencies together. :contentReference[oaicite:0]{index=0}

Correct Answer: To package applications and their dependencies into portable containers

2. How does a Docker container differ from a virtual machine (VM)?

Difficulty: MediumType: MCQTopic: Docker Basics

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All Docker & Kubernetes Interview Questions

Overview

1. What is the primary purpose of using Docker?

2. How does a Docker container differ from a virtual machine (VM)?

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3. Which of the following are the main components of Docker’s architecture?

4. Which command lists all containers including stopped ones?

5. What is the purpose of a Dockerfile in Docker?

6. Explain the difference between a Docker image and a Docker container.

7. What is the correct sequence for a container lifecycle from image to removal?

8. Which default network driver does Docker use for containers on a single host?

9. What is a key difference between Docker volumes and bind mounts?

10. What is Docker Hub used for?

11. What are some best practices when writing Dockerfiles and building images?

12. What are typical security considerations when using Docker in production?

13. What is a Docker image compared to a container?

14. Which command is used to build a Docker image from a Dockerfile?

15. What is the benefit of using image layering in Docker?

16. Why do we tag Docker images (for example myapp:1.0)?

17. Which commands allow you to push and pull Docker images from a registry?

18. What are the reasons to use a private Docker image registry rather than a public one?

19. What is the purpose of a multi-stage build in Dockerfile?

20. What security risks can Docker images carry and how can you mitigate them?

21. Which command helps you remove dangling or unused images in Docker?

22. What common mistakes in Dockerfile layering can cause longer builds or larger images?

23. What is the best practice around tagging images in a CI/CD pipeline to ensure immutability?

24. What is the default network driver used by Docker on a single host?

25. Why would you create a custom Docker network instead of using the default bridge network?

26. What is the purpose of the overlay network driver in Docker?

27. What is a key difference between a Docker bind mount and a Docker volume?

28. Which command syntax mounts a host directory /data into the container’s path /app/data?

29. Explain how Docker volumes help persist data when containers are removed and why that matters.

30. Describe how you would backup data from a Docker volume and restore it to another host.

31. In Docker Compose, which keyword is used to assign an alias to a service within a network so other services can refer to it by that alias?

32. Which command lets you connect a running container to an existing Docker network?

33. What is a tmpfs mount in Docker and when is it useful?

34. What are some security risks associated with Docker volume and network configuration and how can you mitigate them?

35. What is the primary purpose of the docker-compose tool?

36. Which Compose file key is used to specify dependencies so one service starts after another?

37. What is the difference between a Dockerfile and a Compose file?

38. What is the purpose of Docker Swarm mode?

39. Which command initializes a new Docker Swarm on a host?

40. Explain the difference between manager and worker nodes in Docker Swarm.

41. Which command would you use to create a service in Docker Swarm with 3 replicas of the nginx image?

42. What is the key difference when using `docker stack deploy` compared to `docker-compose up`?

43. How do you scale a service in Docker Swarm and what are best practices to follow?

44. In Docker Compose version 3.9+, what feature allows activating only some services in a multi-profile setup?

45. What is a rolling update in Docker Swarm and how does it differ from a blue-green deployment strategy?

46. What is the primary role of Kubernetes in containerised application deployments?

47. Which of the following is a component of the Kubernetes control-plane?

48. What is the difference between a Pod and a Container in Kubernetes?

49. Why are namespaces used in Kubernetes?

50. Which Kubernetes object would you use to manage stateless application updates and ensure pods are replaced in a controlled way?

51. Explain the different Service types in Kubernetes and when you might use each.

52. What is the role of selectors when used with labels in Kubernetes objects?

53. How do you design a highly available Kubernetes control plane and what are key considerations in that design?

54. In Kubernetes, which phase is reached when a pod has been bound to a node and init containers (if any) have completed?

55. What are init containers in Kubernetes and why would you use them?

56. Which command would you use to safely remove a node from scheduling pods in Kubernetes before performing maintenance?

57. What is the main purpose of a Kubernetes Deployment object?

58. Which fields in the Deployment spec control how rolling updates are performed?

59. How can you roll back a Deployment to a previous version?

60. Explain how ConfigMaps and Secrets differ and how you would use them in a Deployment.

61. What happens if you set resource limits but do not set resource requests in a Pod spec?

62. What is the difference between a liveness probe and a readiness probe in Kubernetes?

63. What is immutable configuration in Kubernetes and why is it beneficial for Deployments?

64. Which deployment strategy allows you to gradually shift traffic to a new version while keeping the old version live until it’s safe to switch completely?

65. What are some best practices when writing Kubernetes Deployment YAML manifests?

66. Which command allows you to pause a Deployment rollout for inspection and resume it later?

67. Which statement best describes the Kubernetes cluster networking model?

68. What is the role of a CNI plugin in a Kubernetes cluster?

69. Explain the difference between a Kubernetes Service of type LoadBalancer and an Ingress resource and when you would use each.

70. Which Kubernetes object defines a cluster-level piece of storage that pods can use via a claim?

71. What purpose does a StorageClass serve in Kubernetes?

72. Which controller would you use to automatically scale pods based on CPU usage?

73. When would you use a StatefulSet instead of a Deployment and what storage considerations come into play?

74. What does a Kubernetes NetworkPolicy control?

75. Explain the difference between vertical scaling and horizontal scaling in Kubernetes and provide example use-cases for each.

76. What condition might trigger eviction of a pod from a node in Kubernetes?

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