Docker Tutorial — Architecture Exercises

Practice what you’ve learned about Docker’s architecture, the daemon stack, images vs containers, and Docker Hub.

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Exercise 1 — Trace the Flow

Question: When you type docker run nginx, list the components involved in order.

Show Answer

1. Docker CLI — sends REST API request to daemon
2. Docker Daemon (dockerd) — receives request, checks for image locally, pulls from Docker Hub if needed
3. containerd — prepares the container bundle and filesystem
4. runc — creates namespaces and cgroups, starts the nginx process
5. Container — nginx is now running as an isolated process

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Exercise 2 — Images vs Containers

Question: True or False:

1. An image changes when you create a container from it.
2. You can create multiple containers from the same image.
3. Data written inside a container is lost when the container is removed.
4. Image layers are shared between containers.

Show Answer

1. False — Images are immutable (read-only)
2. True — One image, many containers
3. True — Unless you use volumes for persistent storage
4. True — All containers from the same image share the same layers

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Exercise 3 — Explore Docker Objects

Goal: List all four types of Docker objects on your system.

$ docker image ls
$ docker container ls -a
$ docker volume ls
$ docker network ls

Question: What are the three default networks Docker creates?

Show Answer

1. bridge — default network for containers
2. host — container shares host network stack
3. none — no networking

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Exercise 4 — Docker Hub

Question: What is the full image name when you run docker pull nginx?

Show Answer

docker.io/library/nginx:latest

• docker.io — Docker Hub registry
• library — official images namespace
• nginx — image name
• latest — default tag

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Exercise 5 — Component Roles

Question: Match each component to its role.

Component	Role
dockerd	?
containerd	?
runc	?

Show Answer

Component	Role
dockerd	API server — receives CLI commands, manages images/volumes/networks
containerd	Container lifecycle manager — start, stop, pause, delete containers
runc	Low-level runtime — creates containers using Linux namespaces and cgroups

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