20 Linux Containers Quiz Questions and Answers

Question 1:
What is the primary purpose of Linux containers?
A) To replace traditional operating systems
B) To provide isolated environments for applications
C) To manage hardware resources directly
D) To create physical partitions on a disk

Answer: B
Explanation: Linux containers use kernel features like namespaces and cgroups to isolate processes, allowing applications to run in their own environments without the overhead of a full virtual machine.

Question 2:
Which Linux kernel feature is essential for container isolation?
A) Kernel modules
B) Namespaces
C) System calls
D) File permissions

Answer: B
Explanation: Namespaces in the Linux kernel partition kernel resources, enabling containers to have their own isolated view of the system, such as process IDs and network interfaces.

Question 3:
What command is used to list all running Docker containers?
A) docker ps
B) docker list
C) docker run
D) docker images

Answer: A
Explanation: The `docker ps` command displays a list of all running containers, including their IDs, names, and status, helping users manage container lifecycle.

Question 4:
How do Linux containers differ from virtual machines (VMs)?
A) Containers include a full OS kernel
B) Containers share the host’s kernel
C) VMs are faster to start
D) Containers require more resources

Answer: B
Explanation: Unlike VMs, which run a separate kernel for each instance, containers share the host’s kernel, making them more lightweight and efficient.

Question 5:
Which tool is commonly used for building Docker images?
A) Dockerfile
B) Containerfile
C) Imagebuilder
D) Buildkit

Answer: A
Explanation: A Dockerfile is a text file that contains instructions for building a Docker image, specifying the base image, dependencies, and commands to run.

Question 6:
What does the `docker run` command do?
A) Stops a container
B) Creates and starts a new container
C) Removes a container
D) Lists containers

Answer: B
Explanation: The `docker run` command pulls an image if needed and starts a new container from it, allowing users to execute applications in an isolated environment.

Question 7:
In Kubernetes, what is a Pod?
A) A single container
B) A group of containers
C) A network policy
D) A storage volume

Answer: B
Explanation: A Pod in Kubernetes is the smallest deployable unit and can contain one or more containers that share resources like storage and network.

Question 8:
Which command is used to remove a Docker container?
A) docker delete
B) docker rm
C) docker stop
D) docker purge

Answer: B
Explanation: The `docker rm` command removes one or more containers, but it only works if the container is stopped; otherwise, it must be stopped first.

Question 9:
What is the role of cgroups in Linux containers?
A) To manage user permissions
B) To limit and isolate resource usage
C) To handle network routing
D) To encrypt data

Answer: B
Explanation: Cgroups (control groups) allow the Linux kernel to allocate resources like CPU, memory, and I/O to specific processes, ensuring containers do not overuse system resources.

Question 10:
Which of the following is a container orchestration tool?
A) Git
B) Kubernetes
C) Apache
D) Nginx

Answer: B
Explanation: Kubernetes is an open-source platform designed to automate deploying, scaling, and managing containerized applications across a cluster of machines.

Question 11:
What is the default storage driver used in Docker on most Linux systems?
A) OverlayFS
B) AUFS
C) Device Mapper
D) Btrfs

Answer: A
Explanation: OverlayFS is commonly used as the default storage driver in Docker for Linux because it efficiently layers file systems, enabling quick image builds and container starts.

Question 12:
How can you expose a port from a Docker container to the host?
A) Using the -p flag in docker run
B) Using the -e flag
C) Using the -v flag
D) Using the -it flag

Answer: A
Explanation: The -p flag in the `docker run` command maps a container port to a host port, allowing external access to services running inside the container.

Question 13:
What is LXC in the context of Linux containers?
A) A container runtime
B) A programming language
C) A network protocol
D) A file system

Answer: A
Explanation: LXC (Linux Containers) is a userspace interface for the Linux kernel containment features, providing a lightweight virtualization environment for running multiple isolated Linux systems.

Question 14:
Which command inspects the details of a Docker container?
A) docker inspect
B) docker info
C) docker logs
D) docker stats

Answer: A
Explanation: The `docker inspect` command provides detailed JSON output about a container, including its configuration, network settings, and runtime information.

Question 15:
What security feature is important for running containers in production?
A) Running as root user
B) Using non-root users inside containers
C) Disabling kernel updates
D) Sharing host volumes freely

Answer: B
Explanation: Running containers as non-root users minimizes the risk of privilege escalation attacks, enhancing overall security in production environments.

Question 16:
In Docker, what does the `docker-compose up` command do?
A) Builds images only
B) Starts and runs multi-container applications
C) Removes containers
D) Pulls images

Answer: B
Explanation: The `docker-compose up` command starts and runs an entire application defined in a docker-compose.yml file, which can include multiple interconnected services.

Question 17:
What is a Docker image?
A) A running instance of a container
B) A lightweight, executable package that includes everything needed to run software
C) A script for building containers
D) A network configuration file

Answer: B
Explanation: A Docker image is a snapshot of a container’s file system and configuration, serving as a template for creating runnable containers.

Question 18:
Which namespace is used for isolating the network in Linux containers?
A) PID namespace
B) Mount namespace
C) Network namespace
D) User namespace

Answer: C
Explanation: The network namespace isolates network interfaces, routing tables, and other network resources, allowing each container to have its own network stack.

Question 19:
How do you update a Docker container?
A) By rebuilding the image and recreating the container
B) By using the docker update command
C) By restarting the container
D) By changing the configuration file

Answer: A
Explanation: To update a container, you typically build a new image with the changes and then run a new container from that image, as containers are immutable.

Question 20:
What is the benefit of using containers for application deployment?
A) Increased hardware dependency
B) Faster deployment and scalability
C) Higher resource consumption
D) Limited portability

Answer: B
Explanation: Containers allow for consistent, portable deployment across environments, enabling quick scaling and reducing downtime through efficient resource use.