Home Cognitive Class Docker Essentials: A Developer Introduction Cognitive Class Answers

Docker Essentials: A Developer Introduction Cognitive Class Answers

Docker Essentials A Developer Introduction Cognitive Class Answers

Get Certificate: Docker Essentials: A Developer Introduction

Docker Essentials: A Developer Introduction

Lab 1: Run your first container

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

Lab 2: Add CI/CD value with Docker images

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

  • docker.yml
  • docker.config
  • Dockerfile
  • README.md

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

Lab 3. Orchestrate applications with Docker Swarm

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

  • Declarative
  • Imperative
  • Closed-source
  • Nonexistent

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 : The “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

Final Exam Answers

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 correct
  • 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 1 0:  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


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