Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 171:

  Which of the following commands is used to display system-wide Docker configuration on a host?

  A. docker info
  B. docker status
  C. docker inspect
  D. docker system
  A. docker info

• Question 172:

  A server is running low on disk space. What command can be used to check the disk usage of images, containers, and volumes for Docker engine?

  A. 'docker system df'
  B. 'docker system prune'
  C. 'docker system free'
  D. 'docker system ps'
  A. 'docker system df'

• Question 173:

  You have just executed 'docker swarm leave' on a node. What command can be run on the same node to confirm it has left the cluster?

  A. docker node ls
  B. docker system info
  C. docker system status
  D. docker system status
  B. docker system info

• Question 174:

  Which 'docker run' flag lifts cgroup limitations?

  A. 'docker run --isolation'
  B. 'docker run --cap-drop'
  C. 'docker run --privileged'
  D. 'docker run --cpu-period'
  C. 'docker run --privileged'

• Question 175:

  You created a new service named 'http' and discover it is not registering as healthy. Will this command enable you to view the list of historical tasks for this service? Solution: 'docker service ps http'

  A. Yes
  B. No
  A. Yes

  ---

  Explanation/Reference:

  Using `docker service ps http' enables you to view the list of historical tasks for this service. The docker service ps command shows information about tasks associated with one or more services. A task is a slot where a container runs to execute a service's commands. A task can have different states in its lifecycle, such as new, running, complete, failed, etc. The docker service ps command shows all tasks by default, including historical ones.

• Question 176:

  An application image runs in multiple environments, with each environment using different certificates and ports. Is this a way to provision configuration to containers at runtime?

  Solution: Create a Dockerfile for each environment, specifying ports and Docker secrets for certificates.

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  Creating a Dockerfile for each environment, specifying ports and Docker secrets for certificates, is not a way to provision configuration to containers at runtime. A Dockerfile defines the configuration of an image at build time, not at runtime. Creating a different Dockerfile for each environment is not a good practice, as it introduces duplication and inconsistency. To provision configuration to containers at runtime, you can use environment variables, config objects, or command-line arguments.

• Question 177:

  The Kubernetes yaml shown below describes a clusterIP service.

  

  Is this a correct statement about how this service routes requests?

  Solution: Traffic sent to the IP of any pod with the label app: nginx on port 8080 will be forwarded to port 80 in that pod.

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  Traffic sent to the IP of any pod with the label app: nginx on port 8080 will be forwarded to port 80 in that pod is not a correct statement about how this service routes requests. A clusterIP service does not route requests based on the pod IP, but on the service IP. A clusterIP service also does not forward requests from one port on the pod IP to another port on the same pod IP, but from one port on the service IP to another port on the pod IP. Therefore, this statement is incorrect and does not describe how this service routes requests. References: https://kubernetes.io/docs/concepts/services- networking/service/#defining-a-service, https://kubernetes.io/docs/concepts/services- networking/service/#virtual-ips-andservice-proxies

• Question 178:

  Seven managers are in a swarm cluster.

  Is this how should they be distributed across three datacenters or availability zones?

  Solution: 5-1-1

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  This is not how they should be distributed across three datacenters or availability zones, because having one manager in two datacenters or availability zones creates a risk of losing quorum if those datacenters or availability zones become unavailable. According to the official documentation, managers should be distributed evenly across datacenters or availability zones to ensure that the swarm can survive the loss of any one datacenter or availability zone.

• Question 179:

  Which statement is true?

  A. CMD shell format uses this form ["param", param", "param"]
  B. ENTRYPOINT cannot be used in conjuction with CMD
  C. CMD is used to run the software is the image along with any arguments
  D. ENTRYPOINT cannot be overriden in the "docker container run" command
  A. CMD shell format uses this form ["param", param", "param"]

• Question 180:

  You created a new service named 'http' and discover it is not registering as healthy. Will this command enable you to view the list of historical tasks for this service? Solution: 'docker service inspect http'

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  Using `docker service inspect http' does not enable you to view the list of historical tasks for this service. The docker service inspect command shows low-level information about one or more services, such as their configuration, replicas, networks, endpoints, etc. It does not show the history of tasks that have been run by the service. To view the list of historical tasks for this service, you need to use `docker service ps http'.