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Docker Essentials: A Developer Introduction Cognitive Class Exam Quiz Answers

Docker Essentials: A Developer Introduction Cognitive Class Certification Answers

Question 1: Containers achieve isolation because of what feature in the Linux kernel?

  • Namespaces
  • Memory Swap management
  • SystemD init system
  • Permissions mechanisms

Question 2: What is the difference between a Docker container and a Docker image?

  • Nothing: these are two words for the same thing.
  • An image is the blueprint for spinning up containers. An image is a TAR of a file system, and a container is a file system plus a set of processes running in isolation.
  • Images are used to create the host machine that runs the Docker Engine.
  • Images are used only as a backup and restore mechanism for containers.

Question 3: Control groups (cgroups) limit and monitor resources.

  • True
  • False

Question 4: Which statement is not true about Docker?

  • Docker makes it easier to package applications and add to CI/CD pipelines.
  • Docker helps you package dependencies with containers.
  • Docker invented containers and Linux namespaces.
  • Docker simplifies container technology to make creating and running containers easier.

Question 5: What tool makes it possible to run Docker containers on operating systems other than Linux?

  • LinuxByte
  • OSContainers
  • Docker Swarm
  • LinuxKit

Question 1: Which file should you use to create reproducible builds for Docker images?

  • docker.yml
  • docker.config
  • Dockerfile

Question 2: To rebuild and re-push images quickly, you should optimize your Dockerfile for what?

  • Reproducibility: ensures your Dockerfile will create the same image every time it is built
  • Documentation: helps other engineers build and push images faster
  • Time to market: enables business users to get their features out faster
  • The layer cache: put lines that change more frequently near the end of the file

Question 3: You must use Docker Hub as the central registry to share the Docker images that you create.

  • True
  • False

Question 4: What’s the purpose of the FROM line in a dockerfile? Select all that apply.

  • It executes commands needed to set up your image for an application.
  • It’s required as the first line in a Dockerfile.
  • It copies a file into a directory.
  • It specifies the starting image to build other image layers on top of.

Question 5: What does this command do: $ docker system prune.

  • Stops and removes containers
  • Stops running containers
  • Retrieves a list of running containers
  • Removes containers that are already stopped

Question 1: What is the operational model used by Docker Swarm for managing a cluster?

  • Declarative
  • Imperative
  • Closed-source
  • Non-existent

Question 2: What effect does the routing mesh have on a Docker swarm cluster?

  • Commands, such as “docker service create,” that are sent to any node on the cluster will be routed to a manager that can respond to those commands.
  • Requests that are sent to a published port on any node of the swarm will automatically be routed to a node that is running a container for that service.
  • Every service that is created on the cluster will schedule at least one container for every node in the cluster to ensure global availability.
  • You can enable the routing mesh to use layer-7 load balancing in front of your running containers.

Question 3: he “docker swarm init command” generates a join token. What is the purpose of that token?

  • It allows you to remotely control production applications.
  • It initializes a swarm.
  • It makes sure that no malicious nodes join the swarm.
  • It outputs nodes in a swarm.

Question 4: When you run the following command, which of the following events does not occur?

$ docker service update –replicas=5 –detach=true nginx1


  • The state of the service is updated to 5 replicas, which is stored in the swarm’s internal storage.
  • Docker Swarm recognizes that the number of replicas that is scheduled now does not match the declared state of 5.
  • This command checks aggregated logs on the updated replicas.
  • Docker Swarm schedules 5 more tasks (containers) in an attempt to meet the declared state for the service.

Question 5: The more manager nodes you have, the easier it is to achieve a consensus on the state of a cluster.

  • True
  • False

Question 1: What is one advantage of isolation that is provided by containers?

  • Container isolation provides a mechanism for immutable infrastructure.
  • Containers running in isolation means that you don’t have to deal with conflicting dependencies that are installed on the host or other containers.
  • Isolated containers make it easier to monitor applications running inside of containers.
  • Each isolated container provides you with an SSH server that can be used for debugging or automation purposes.

Question 2: What factors should you consider when you choose your FROM image?

  • Size
  • Security
  • Source
  • All of these

Question 3: What is the best way to distribute a Dockerized application to different environments?

  • Maven Nexus repository
  • Docker registry
  • Source control
  • Any of these

Question 4: What is a good starting point for the number of manager nodes in a cluster?

  • 3
  • 1
  • 4
  • > 10

Question 5: Running containerized applications in production can come with a variety of problems. Which of the following items is not a problem of running a containerized application in production?

  • Scheduling containers across a distributed cluster
  • High availability
  • Scaling
  • “Works on my machine” syndrome

Question 6: What is one advantage of using containers across different environments?

  • Deploying containers only once, and Docker will deploy across all environments automatically
  • Avoiding environmental drift caused by maintaining multiple environments
  • Redeploying containers
  • Creating independent applications

Question 7: You need an SSH server to get a bash shell inside a container.

  • True
  • False

Question 8: What technologies are behind Docker’s image layering system?

  • Linux namespaces and control groups
  • Storage driver plugins
  • Union file system and copy-on-write
  • Docker build and push caching

Question 9: What is the result of running the command “docker run ubuntu:15.04” 1000 times on your workstation?

  • Your workstation will run 1000 Ubuntu containers and will likely handle this just fine.
  • Your workstation will crash from being out of space if it’s running with 100 GB of storage or less.
  • Your workstation will crash from being out of memory if it’s running with less than 4 GB of RAM.
  • The developer-friendly interface of the Docker CLI will prevent you from doing something so silly.

Question 10: Open-source container orchestration platforms, such as Docker Swarm and Kubernetes, provide what to their users?

  • A way to orchestrate different flavors of the same application in a way that maximizes reuse
  • A fully hosted solution that is production-ready for deploying enterprise grade applications
  • An easy-to-use GUI for operators to click and deploy applications
  • A platform to help solve problems of running distributed containerized applications in production, such as high availability, scaling, fault tolerance, and scheduling

Introduction to Docker Essentials: A Developer Introduction

“Introduction to Docker Essentials: A Developer Introduction” is a comprehensive guide aimed at developers looking to familiarize themselves with Docker, a popular containerization platform. This introduction serves as a primer for understanding the fundamental concepts and practical applications of Docker in software development environments.

  1. Containerization Basics: It explains the concept of containerization and how Docker enables developers to package applications and their dependencies into standardized units called containers.
  2. Docker Architecture: An overview of Docker’s architecture, including Docker Engine, Docker Images, and Docker Containers. This section helps developers understand how Docker components work together to create and manage containers.
  3. Docker Installation and Setup: Step-by-step instructions for installing Docker on various operating systems such as Windows, macOS, and Linux. It also includes guidance on configuring Docker for development purposes.
  4. Working with Docker Images: Explains how to create Docker images using Dockerfiles, which are text files that contain instructions for building images. It covers best practices for creating efficient and secure images.
  5. Container Management: Techniques for managing Docker containers, including starting, stopping, and removing containers. It also covers container networking and data management.
  6. Docker Compose: Introduction to Docker Compose, a tool for defining and running multi-container Docker applications. It explains how to use Docker Compose to define application services and their dependencies.
  7. Container Orchestration: An overview of container orchestration platforms such as Kubernetes and Docker Swarm. It discusses the benefits of orchestration for deploying and managing containerized applications at scale.
  8. Continuous Integration and Deployment (CI/CD): How Docker integrates with CI/CD pipelines to automate the build, test, and deployment processes. It covers strategies for incorporating Docker into development workflows for improved efficiency and reliability.
  9. Best Practices and Tips: Provides best practices for designing, building, and managing Dockerized applications. It includes tips for optimizing container performance, improving security, and troubleshooting common issues.

Overall, “Introduction to Docker Essentials: A Developer Introduction” equips developers with the knowledge and skills needed to leverage Docker effectively in their development workflows, enabling them to build, deploy, and manage containerized applications with confidence.

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