DCA Exam Dumps : Docker Certified Associate (DCA) Exam

= 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

= The purpose of Docker Content Trust is to sign and verify image tags using digital signatures for data sent to and received from remote Docker registries12. This allows client-side or runtime verification of the integrity and publisher of specific image tags, ensuring the provenance and security of container images34. References:

• 1: Content trust in Docker | Docker Docs
• 2: Docker Content Trust: What It Is and How It Secures Container Images
• 3: Docker Content Trust in Azure Pipelines - Azure Pipelines
• 4: 4.5 Ensure Content trust for Docker is Enabled | Tenable®

 Multi-stage builds are a feature of Docker that allows you to use multiple FROM statements in your Dockerfile. Each FROM statement creates a new stage of the build, which can use a different base image and run different commands. You can then copy artifacts from one stage to another, leaving behind everything you don’t want in the final image. This optimizes the image size and reduces the attack surface by removing unnecessary dependencies and tools. For example, you can use a stage to compile your code, and then copy only the executable file to the final stage, which can use a minimal base image like scratch. This way, you don’t need to include the compiler or the source code in the final image. References:

• Multi-stage builds | Docker Docs
• What Are Multi-Stage Docker Builds? - How-To Geek
• Multi-stage | Docker Docs