Docker-Bundle

Question 1

What is Docker?

Answer 1

Docker is an open-source platform for developing, shipping, and running applications inside lightweight, portable containers.

Question 2

What are Docker containers?

Answer 2

Docker containers are isolated environments created using Docker, where applications can run with their dependencies.

Question 3

How does Docker differ from virtual machines?

Answer 3

Docker containers share the host system’s kernel, are more lightweight, and start faster compared to virtual machines that have full-blown operating systems.

Question 4

What is a Docker image?

Answer 4

A Docker image is a lightweight, standalone, executable package that includes everything needed to run a piece of software, including the code, runtime, libraries, environment variables, and config files.

Question 5

What is a Dockerfile?

Answer 5

A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.

Question 6

How do you create a Docker container?

Answer 6

By using the docker run command along with various options and an image name.

Question 7

What is Docker Hub?

Answer 7

Docker Hub is a cloud-based registry service that allows you to link to code repositories, build your images, test them, store manually pushed images, and link to Docker Cloud.

Question 8

How do you stop a Docker container?

Answer 8

Use docker stop <container_id> to gracefully stop a container. You can also use docker kill <container_id> for a forceful stop.</container_id></container_id>

Question 9

Explain the role of the docker ps command.

Answer 9

The docker ps command is used to list the running containers.

Question 10

How do you list all Docker containers?

Answer 10

Use docker ps -a to list all containers, including the ones that are stopped.

Question 11

What are Docker network drivers?

Answer 11

Network drivers provide the networking capabilities for containers. Common types include bridge, host, overlay, macvlan, and none.

Question 12

Explain Docker bridge network.

Answer 12

The default network driver for Docker. When you run a container with the docker run command, it automatically connects to this network.

Question 13

How do you create a Docker network?

Answer 13

Use docker network create followed by options and the network name.

Question 14

Can Docker containers communicate with each other by default?

Answer 14

Containers on the same network can communicate with each other. Containers on different networks need explicit port mapping.

Question 15

What is port mapping in Docker?

Answer 15

Port mapping is the process of mapping a port on the host to a port in the container to allow external access to the container.

Question 16

What are Docker volumes?

Answer 16

Docker volumes are the preferred way of handling persistent data created by and used by Docker containers.

Question 17

How do you create a Docker volume?

Answer 17

Use docker volume create <volume_name>.</volume_name>

Question 18

Explain bind mounts in Docker.

Answer 18

Bind mounts are a type of mount that allows you to store container data on the host system.

Question 19

What is the difference between a Docker volume and a bind mount?

Answer 19

Docker volumes are managed by Docker and are isolated from the core functionality of the host machine, whereas bind mounts may depend on the directory structure and OS of the host machine.

Question 20

How do you backup a Docker volume?

Answer 20

By creating a backup container that mounts the volume and then using docker cp to copy the volume to a backup location.

Question 21

What is Docker Compose?

Answer 21

Docker Compose is a tool for defining and running multi-container Docker applications.

Question 22

How do you define services in Docker Compose?

Answer 22

Services are defined in a docker-compose.yml file where you can specify multiple containers and their configurations.

Question 23

What is the purpose of a Docker Swarm?

Answer 23

Docker Swarm is a clustering and scheduling tool for Docker containers. It turns a pool of Docker hosts into a single, virtual host.

https://docs.docker.com/engine/swarm/how-swarm-mode-works/nodes/

Question 24

How do you scale services in Docker?

Answer 24

In Docker Swarm, you can scale services using the docker service scale command. In Docker Compose, use docker-compose up –scale command.

Question 25

What is a Docker Stack?

Answer 25

A Docker stack is a group of interrelated services that share dependencies and are orchestrated and scaled together.

Question 26

How do you ensure security in Docker?

Answer 26

By using secure images, scanning for vulnerabilities, implementing strong access control, using signed images, and keeping the Docker environment updated.

Question 27

What are Docker security best practices?

Answer 27

Some best practices include running containers with the least privileges, using non-root users inside containers, regularly updating images, and avoiding storing secrets in Dockerfiles.

Question 28

Explain Docker Content Trust.

Answer 28

Docker Content Trust provides the ability to use digital signatures for data sent to and received from remote Docker registries.

Question 29

What is the purpose of namespaces in Docker?

Answer 29

Namespaces provide isolation for Docker containers. Each aspect of a container runs in a separate namespace and its access is limited to that namespace.

Question 30

How does Docker use cgroups?

Answer 30

Docker uses cgroups (Control Groups) to limit and isolate the resource usage (CPU, memory, network, etc.) of containers.

Question 31

Explain the Docker daemon.

Answer 31

The Docker daemon (dockerd) is a persistent process that manages Docker containers and handles container objects.

Question 32

What is a Docker Registry?

Answer 32

A Docker registry is a storage and distribution system for named Docker images.

Question 33

How do you monitor Docker containers?

Answer 33

Docker containers can be monitored using tools like Docker stats, cAdvisor, Prometheus, and Grafana.

Question 34

What are Docker tags?

Answer 34

Docker tags are alphanumeric identifiers attached to images, usually to indicate version information.

Question 35

Explain the Docker image layering system.

Answer 35

Docker images are composed of layers, each representing a set of changes. Layers are cached and shared between images to optimize storage and speed up image building.

Question 36

How can you update a service without downtime in Docker?

Answer 36

By using rolling updates in Docker Swarm, which gradually updates containers in a service with zero downtime.

Question 37

What is Docker’s role in microservices architecture?

Answer 37

Docker containers are ideal for microservices due to their lightweight nature, allowing each microservice to be deployed independently in its container.

Question 38

How do you manage configuration in Docker?

Answer 38

Configurations can be managed using environment variables, configuration files mounted as volumes, or Docker secrets in Swarm.

Question 39

What is a Docker Engine?

Answer 39

Docker Engine is the core part of Docker, a client-server application with the Docker daemon, REST API, and CLI.

Question 40

How do you debug a Docker container?

Answer 40

Debugging can be done by checking container logs using docker logs, using docker exec to access the container shell, or employing external debugging tools.