DCA Online Practice Questions and Answers

Correct Answer: A

This command will display a list of volumes for a specific container, because it uses docker container inspect to show detailed information about a container, including its volumes. According to the official documentation, docker container inspect will show the Mounts section that contains information about all volumes mounted by the container.

Correct Answer: B

Using docker inspect http does not enable you to view the list of historical tasks for this service. The docker inspect command shows low-level information about one or more objects, such as containers, images, networks, etc. It does not show information about services or tasks. To view the list of historical tasks for this service, you need to use docker service ps http --no-trunc.

Correct Answer: A

This statement is correct. A Dockerfile provides instructions for building a Docker image. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using docker build, you can create an automated build that executes several command-line instructions in succession.

Correct Answer: A

This set of commands can identify the published port(s) for a container, because docker container inspect can show the port mappings for a container and docker port can list the public port that is NAT-ed to the private port. According to the official documentation, these commands can be used to find the exposed ports for a container.

Correct Answer: B

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

Correct Answer: B

Using `docker ls -a' does not list all nodes in a swarm cluster from the command line. The docker ls command is not a valid command. To list containers, you need to use `docker container ls' or `docker ps'. To list images, you need to use `docker image ls' or `docker images'. To list nodes in a swarm cluster, you need to use `docker node ls'.

Correct Answer: A

Correct Answer: A

This set of commands can identify the published port(s) for a container. The docker container inspect command shows low-level information about a container in JSON format. This information includes the network settings of the container, such as the port bindings and exposed ports. The docker port command shows the public port(s) that are mapped to a private port inside the container. By using these two commands, you can identify the published port(s) for a container.

Correct Answer: A

Running docker engine activate does upgrade Docker Engine CE to Docker Engine EE. The docker engine activate command is a convenience script that automates the process of uninstalling Docker Engine CE and installing Docker Engine EE on supported platforms. It requires an activation token or license file that can be obtained from Docker Hub or Docker Store.

Correct Answer: A

Using docker container inspect nginx does display a list of volumes for a specific container. The docker container inspect command shows low-level information about one or more containers in JSON format. This information includes various details about the container's configuration, state, network settings, mounts, etc. To display a list of volumes for a specific container, you can either look at the Mounts section in the JSON output or use --format `{{ .Mounts }}' to filter out only that section.