Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 31:

  Does this command display all the pods in the cluster that are labeled as 'env: development'? Solution: 'kubectl get pods --all-namespaces -label env=development'

  A. Yes
  B. No
  B. No

• Question 32:

  From a DevOps process standpoint, it is best practice to keep changes to an application in version control. Which of the following will allow changes to a docker Image to be stored in a version control system?

  A. docker commit
  B. docker save
  C. A docker-compose.yml file
  D. A dockerfile
  A. docker commit

• Question 33:

  In the context of a swarm mode cluster, does this describe a node?

  Solution: an instance of the Docker CLI connected to the swarm

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  An instance of the Docker CLI connected to the swarm does not describe a node in the context of a swarm mode cluster. A node is a physical or virtual machine that runs the Docker Engine and participates in the swarm. A node can have one

  of two roles:

  manager or worker. Manager nodes maintain the cluster state and orchestrate tasks. Worker nodes execute tasks assigned by manager nodes. An instance of the Docker CLI connected to the swarm is a client that can interact with the

  swarm using commands such as docker service, docker node, docker stack, etc. A client can connect to any manager node in the swarm using the --host or -H flag.

• Question 34:

  Which of the following commands wifi automatically create a volume when a container is started?

  A. 'docker container run --name nginxtest --volumes=/app nginx'
  B. 'docker container run --name nginxtest -v /app:mount nginx'
  C. 'docker container run --name nginxtest --volumes myvol:/app:new nginx'
  D. 'docker container run --name nginxtest -v myvol:/app nginx'
  A. 'docker container run --name nginxtest --volumes=/app nginx'

• Question 35:

  Which one of the following commands will result in the volume being removed automatically once the container has exited?

  A. 'docker run --del -v /foo busybox'
  B. 'docker run --read-only -v /foo busybox'
  C. 'docker run --rm -v /foo busybox'
  D. 'docker run --remove -v /foo busybox'
  C. 'docker run --rm -v /foo busybox'

• Question 36:

  Which of the following is required to install Docker EE from a package repository?

  A. Repository URL obtained from Docker Store
  B. License key obtained from Docker Store
  C. Repository URL obtained from Docker Hub
  D. License key obtained from Docker Hub
  A. Repository URL obtained from Docker Store

• Question 37:

  Which of the following modes can be used for service discovery of a Docker swarm service (Pick 2 correct answers)

  A. Virtual IP (VIP) with --endpoint-mode vip
  B. Overlay with --endpoint-mode overlay
  C. DNS Round-Robin with --endpoint-mode dnsrr
  D. Ingress with --endpoint-mode ingress
  E. Network Address Translation(NAT) with --endpoint-mode nat
  A. Virtual IP (VIP) with --endpoint-mode vip
  C. DNS Round-Robin with --endpoint-mode dnsrr

• Question 38:

  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: Kubernetes automatically triggers a user-defined script to attempt to fix the unhealthy container.

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Kubernetes does not automatically trigger a user-defined script to attempt to fix the unhealthy container, because Kubernetes does not have such a feature. According to the official documentation, Kubernetes only supports three types of probes: exec, httpGet, and tcpSocket, and none of them can execute arbitrary scripts.

• Question 39:

  A company's security policy specifies that development and production containers must run on separate nodes in a given Swarm cluster.

  Can this be used to schedule containers to meet the security policy requirements?

  Solution: resource reservation

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Resource reservation cannot be used to schedule containers to meet the security policy requirements, because resource reservation only affects the available resources on a node and does not restrict which containers can run on which nodes. According to the official documentation, resource reservation is used to ensure that a service has enough resources to run. References: https://docs.docker.com/engine/swarm/services/#reserve-memory-or-cpus-for- a-service

• Question 40:

  You configure a local Docker engine to enforce content trust by setting the environment variable DOCKER_C0NTENT_TRUST=l. If myorg/myimage: 1.0 is unsigned, does Docker block this command? Solution: docker image build, from a Dockeflle that begins FROM myorg/myimage: l1.0

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Docker blocks this command if you configure a local Docker engine to enforce content trust by setting the environment variable DOCKER_CONTENT_TRUST=1 and if myorg/myimage:1.0 is unsigned. Content trust is a feature that allows you to use digital signatures to verify the integrity and publisher of specific image tags. When you enable content trust, you can only pull, run, or build with trusted images. If an image tag is unsigned, Docker will block any command that attempts to use it. This includes docker image build, from a Dockerfile that begins FROM myorg/myimage:1.0, if myorg/myimage:1.0 is unsigned.