DCA Online Practice Questions and Answers

Correct Answer: A

Correct Answer: C

Correct Answer: A

Correct Answer: B

Deleting `/var/lib/docker' directory does not upgrade Docker Engine CE to Docker Engine EE. The `/var/lib/docker' directory is where Docker stores all its data and metadata related to containers, images, volumes, networks, etc. Deleting this directory will remove all your Docker data and configurations from your system, but it will not change your Docker version or edition. To upgrade Docker Engine CE to Docker Engine EE, you need to uninstall `docker-ce' package before installing `docker-ee' package.

Correct Answer: B

The networkPolicy will not block this traffic because it does not apply to pods that have the tier: backend label. The networkPolicy only applies to pods that have the tier: frontend label, as specified by the podSelector field. Pods that have the tier: backend label are not affected by this networkPolicy and can receive traffic from any source.

Correct Answer: A

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.

Correct Answer: A

Using `docker node ls' lists all nodes in a swarm cluster from the command line. The docker node command is used to manage nodes in a swarm. The docker node ls subcommand displays information about the nodes in the swarm, such as their ID, hostname, status, availability, and role.

Correct Answer: B

Correct Answer: B

Correct Answer: B

SELinux is not blocking this operation. SELinux is a security module that enforces mandatory access control policies on Linux systems. SELinux can restrict the actions of processes and users based on their security contexts and labels. However, SELinux does not prevent a user from setting the system time from inside a Docker container. The reason why a user's attempts to set the system time from inside a Docker container are unsuccessful is because Docker containers share the same kernel and clock as the host by default. Therefore, changing the system time inside a container requires privileged access to the host kernel, which is not allowed by default for security reasons. To allow a user to set the system time from inside a Docker container, you need to run the container with the --privileged flag or the --cap-add SYS_TIME flag.