Docker Certified Associate (DCA) Certification Practice Test

The command that is used to start a Docker container from an image is "docker run". This command not only creates a container from the specified image but also starts it immediately. When a user runs this command, Docker will first check if the image exists locally. If it is not found, Docker will attempt to pull it from a configured Docker registry. Upon successfully retrieving the image, it will then initiate the container, execute any specific command provided, and configure the environment as specified in the command options.

Other commands listed serve different purposes: "docker create" is used to create a container but does not start it; "docker build" is for building images from a Dockerfile; and "docker launch" is not a standard Docker command. Recognizing the specific role of each command is essential for effectively managing containers and images in Docker.