Docker MCQ Questions with answers and solutions Page 33

Q. What does `VOLUME` do in Dockerfile?

(A) Removes files from image
(B) Creates persistent storage
(C) Increases image size
(D) Disables logging

💬 Discuss

✅ Correct Answer: (B) Creates persistent storage

Explanation: `VOLUME` defines mount points for persistent or shared data.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. Which instruction is best for downloading dependencies during image build?

(A) COPY
(B) ADD
(C) RUN curl
(D) RUN

💬 Discuss

✅ Correct Answer: (D) RUN

Explanation: `RUN` is used to execute commands like `apt-get`, `curl`, or `npm install` during image build.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. What’s the difference between `ADD` and `COPY`?

(A) `ADD` has more features than `COPY`
(B) `COPY` can extract archives
(C) `ADD` only copies files
(D) `COPY` supports remote URLs

💬 Discuss

✅ Correct Answer: (A) `ADD` has more features than `COPY`

Explanation: `ADD` supports features like extracting archives and handling URLs, while `COPY` is more straightforward.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. Which Dockerfile instruction defines the user to run subsequent commands?

(A) USER
(B) RUNAS
(C) EXEC
(D) LOGIN

💬 Discuss

✅ Correct Answer: (A) USER

Explanation: `USER` sets the UID or username for running following commands in the image.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. How can you reduce image size while writing Dockerfiles?

(A) Use larger base images
(B) Avoid multi-stage builds
(C) Use multi-stage builds
(D) Use many RUN instructions

💬 Discuss

✅ Correct Answer: (C) Use multi-stage builds

Explanation: Multi-stage builds help create lightweight, optimized final images by separating build and runtime stages.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. What is the default shell in Dockerfile on Linux containers?

(A) cmd
(B) /bin/bash
(C) /bin/sh -c
(D) /usr/shell

💬 Discuss

✅ Correct Answer: (C) /bin/sh -c

Explanation: Docker uses `/bin/sh -c` as the default shell on Linux unless overridden.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. Which instruction can be used to copy files with permission changes?

(A) COPY --chmod
(B) ADD --perm
(C) RUN cp
(D) USER chmod

💬 Discuss

✅ Correct Answer: (A) COPY --chmod

Explanation: `COPY` supports the `--chmod` flag to set file permissions during copying.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. Which instruction should be used to clean up cache during image build?

(A) CMD clean
(B) RUN rm -rf /var/cache && apt-get clean
(C) CLEAN
(D) RESET

💬 Discuss

✅ Correct Answer: (B) RUN rm -rf /var/cache && apt-get clean

Explanation: Cleaning up within a single `RUN` layer reduces final image size.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. How do you override a CMD at runtime?

(A) Using docker override
(B) By editing the image
(C) By providing a command in `docker run`
(D) You cannot override CMD

💬 Discuss

✅ Correct Answer: (C) By providing a command in `docker run`

Explanation: You can override CMD by passing a command after the image name in `docker run`.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Q. What happens if both `CMD` and `ENTRYPOINT` are defined?

(A) `CMD` is ignored
(B) `ENTRYPOINT` runs first
(C) `CMD` arguments are passed to `ENTRYPOINT`
(D) `CMD` and `ENTRYPOINT` conflict

💬 Discuss

✅ Correct Answer: (C) `CMD` arguments are passed to `ENTRYPOINT`

Explanation: If both are defined, `CMD` provides arguments to `ENTRYPOINT` unless CMD is overridden.

Published by Mr. Dubey ⭐ 111.54K Points at 24-Jul-2025 07:06 am in Docker

Docker MCQs with answers Page - 33

Q. What does `VOLUME` do in Dockerfile?

Q. Which instruction is best for downloading dependencies during image build?

Q. What’s the difference between `ADD` and `COPY`?

Q. Which Dockerfile instruction defines the user to run subsequent commands?

Q. How can you reduce image size while writing Dockerfiles?

Q. What is the default shell in Dockerfile on Linux containers?

Q. Which instruction can be used to copy files with permission changes?

Q. Which instruction should be used to clean up cache during image build?

Q. How do you override a CMD at runtime?

Q. What happens if both `CMD` and `ENTRYPOINT` are defined?

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