Quiz

Test your understanding of the concepts covered in the Hello World chapter.

Q1. In Docker terminology, what is the precise relationship between a Docker Image and a Docker Container?

A An Image is a executable running process, whereas a Container is a stored zip file on disk B An Image is an immutable blueprint containing code and libraries, while a Container is a runnable instance created from an image C There is no difference; Image and Container are interchangeable terms for the same concept D Containers exist only in cloud registries, while Images exist only on your local machine

Explanation

Images serve as read-only blueprints (templates) of your application, whereas Containers are the isolated, runnable instances instantiated from those images.

Q2. Which command downloads a Docker image (such as `busybox`) from Docker Hub to your local machine without executing it?

A docker pull busybox B docker fetch busybox C docker download busybox D docker get busybox

Explanation

The `docker pull` command fetches the specified image from a remote registry (like Docker Hub) and saves it to your local Docker image cache.

Q3. If you create a text file inside an interactive container shell (`docker run -it busybox sh`) and then exit, what happens when you start a new container from the same image?

A The text file will automatically appear in the new container B The text file will be saved to your host machine's desktop C The text file will not be present because containers are isolated, fresh instances D Docker will throw a file conflict error and refuse to start

Explanation

Docker containers feature isolated, ephemeral file systems. Changes made inside one container instance do not persist into new container instances unless mounted to volumes.

Q4. Which flag passed to `docker run` automatically cleans up and deletes the container instance once its process completes?

A --rm B --clean C -d D --auto-delete

Explanation

The `--rm` flag instructs Docker to remove the container and its temporary file system automatically as soon as it exits, preventing disk clutter.

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