Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 191:

  Which statement is correct about cluster management in Docker Enterprise Edition 3.x?

  A. Clusters can contain Windows 10 and Windows Server 2016 only.
  B. Clusters can contain Linux, Windows Server 2016 and 2019, and Linux on IBM z Systems.
  C. Clusters can contain Linux only.
  D. Clusters can contain Linux and Windows Server 2008 R2 only.
  A. Clusters can contain Windows 10 and Windows Server 2016 only.

• Question 192:

  The output of which command can be used to find the architecture and operating system an image is compatible with?

  A. docker image inspect --filter {{.Architecture}} {{.OS}} '
  B. docker image ls
  C. docker image inspect --format {{.Architecture}} {{.OS}} '
  D. docker image info
  C. docker image inspect --format {{.Architecture}} {{.OS}} '

• Question 193:

  The following Docker Compose file is deployed as a stack:

  

  Is this statement correct about this health check definition?

  Solution: Health checks test for app health ten seconds apart. Three failed health checks transition the container into "unhealthy" status.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This statement is correct about this health check definition. A health check is a feature that allows Docker to monitor the health status of a container by running a command in the container periodically. A health check has three parameters: test, interval, and retries. The test parameter specifies the command to run to check the health of the container. The interval parameter specifies how often to run the health check. The retries parameter specifies how many consecutive failures of the health check are needed to mark the container as unhealthy. In this case, the health check runs curl -f http://localhost/ || exit 1 every 10 seconds to test for app health. If this command fails three times in a row, the container is marked as unhealthy.

• Question 194:

  One of several containers in a pod is marked as unhealthy after failing its livenessProbe many times. Is this the action taken by the orchestrator to fix the unhealthy container? Solution: The unhealthy container is restarted.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  The unhealthy container is restarted by the orchestrator to fix the unhealthy container, because this is the default behavior of Kubernetes when a container fails its livenessProbe. According to the official documentation, Kubernetes will kill and restart the container if it does not become healthy after a certain number of failures.

• Question 195:

  Some Docker images take time to build through a Continuous Integration environment. You want to speed up builds and take advantage of build caching. Where should the most frequently changed part of a Docker image be placed in a Dockerfile?

  A. at the bottom of the Dockerfile
  B. after the FROM directive
  C. at the top of the Dockerfile
  D. in the ENTRYPOINT directive
  A. at the bottom of the Dockerfile

• Question 196:

  Two development teams in your organization use Kubernetes and want to deploy their applications while ensuring that Kubernetes-specific resources, such as secrets, are grouped together for each application.

  Is this a way to accomplish this?

  Solution: Create one namespace for each application and add all the resources to it.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This is a way to accomplish this, because creating one namespace for each application and adding all the resources to it is a good practice for deploying applications in Kubernetes. According to the official documentation, namespaces are used to group resources into logical units that correspond to different projects, teams, or environments. Using namespaces can help avoid naming collisions and enforce resource quotas and access policies.

• Question 197:

  Will this command ensure that overlay traffic between service tasks is encrypted? Solution: docker network create -d overlay -o encrypted=true

  A. Yes
  B. No
  A. Yes

• Question 198:

  How do you configure Docker engine to use a registry that is not configured with TLS certificates from a trusted CA?

  A. Set IGNORE_TLS in the 'daemon.json' configuration file.
  B. Set and export the IGNORE_TLS environment variable on the command line
  C. Set INSECURE_REGISTRY in the '/etc/docker/default' configuration file
  D. Pass the '--insecure.-registry' flag to the daemon at run time
  D. Pass the '--insecure.-registry' flag to the daemon at run time

• Question 199:

  What is used by the kernel to Isolate resources when running Docker containers?

  A. Namespaces
  B. Overlay networks
  C. Volumes
  D. Control groups (also know as cgroups)
  D. Control groups (also know as cgroups)