The docker ps command is used to list all currently running containers. This command provides a snapshot of the active containers, including their container ID, the image they are based on, the command being run, creation time, status, ports, and names. This is the most direct way for an administrator to validate which containers are in a running state to begin troubleshooting an application accessibility issue.

A. docker start is used to start one or more containers that are in a stopped state, not to list them.

C. docker run creates and starts a new container from a specified image; it does not list existing containers.

D. docker images lists the container images that have been downloaded to the local host, not the running container instances.

1. Docker Inc. (2024). "docker ps". Docker Docs. Retrieved from https://docs.docker.com/engine/reference/commandline/ps/. The official documentation specifies

"List containers. The default is to show only running containers."

2. Pahl

C.

& Jamshidi

P. (2016). Microservices: A Systematic Mapping Study. In 6th International Conference on Cloud Computing and Services Science (CLOSER) (pp. 137-146). SCITEPRESS – Science and Technology Publications. DOI: 10.5220/0005789201370146. The paper discusses container management

where listing running instances (docker ps) is a fundamental operational task.