Docker Certified Associate DCA Exam Dumps

 The sequence of steps will not completely delete an image from disk in the Docker Trusted Registry. Deleting an image and deleting an image repository from the Docker Trusted Registry will only remove the references to the image, but not the actual image data on the disk1. To completely delete an image from disk, you need to run the garbage collection command on the registry server, which will delete any unreferenced blobs2. The garbage collection command is bin/registry garbage-collect /path/to/config.yml3. References: Deleting an image), Garbage collection), Running garbage collection)

= I cannot give you a comprehensive explanation, but I can tell you that the question is about Kubernetes, not Docker. Kubernetes is an orchestrator that can manage multiple containers in a pod, which is a group of containers that share a network and storage. A livenessProbe is a way to check if a container is alive and ready to serve requests. If a container fails its livenessProbe, Kubernetes will try to restart it by default. However, you can also specify a custom action to take when a container fails its livenessProbe, such as running a script to fix the problem. This is what the solution is referring to. You will need to understand the difference between Kubernetes and Docker, and how they work together, to answer this question correctly. References: You can find some useful references for this question in the following links:

• Kubernetes Pods
• Configure Liveness, Readiness and Startup Probes
• Docker and Kubernetes

 = The command ‘docker service ps http’ will list the tasks that are running as part of the ‘http’ service, as well as the task history1. The task history shows the previous states of the tasks, such as running, shutdown, rejected, etc. This can help you troubleshoot why the service is not registering as healthy, by looking at the current state, error, and ports of each task1. References:

• docker service ps | Docker Docs
• Docker Certified Associate Guide
• DCA Prep Guide

= A Dockerfile does not store persistent data between deployments of a container. A Dockerfile is a text document that contains instructions for building a Docker image. A Docker image is a read-only template that defines the layers and configuration of a container. A Docker container is an isolated and ephemeral instance of a Docker image that runs on the Docker Engine. Docker containers are not meant to store persistent data, as any changes made to the container’s filesystem are lost when the container is removed. To store persistent data between deployments of a container, you need to use volumes or bind mounts. Volumes and bind mounts are ways to attach external storage to a container, so that the data is preserved even if the container is deleted. Volumes are managed by Docker and stored in a location on the host system that is independent of the container’s lifecycle. Bind mounts are files or directories on the host system that are mounted into a container. References:

• Persist container data
• Dockerfile reference
• Docker MySQL Persistence
• Persist the DB
• Docker - Dockerfile, persist data with VOLUME