Docker DCA Practice Test - Questions Answers, Page 4

A liveness probe is a mechanism for indicating your application's internal health to the Kubernetes control plane. Kubernetes uses liveness probes to detect issues within your pods.When a liveness check fails, Kubernetes restarts the container in an attempt to restore your service to an operational state1. Therefore, the action taken by the orchestrator to fix the unhealthy container is to restart it.Reference:

Content trust in Docker | Docker Docs

Docker Content Trust: What It Is and How It Secures Container Images

A Practical Guide to Kubernetes Liveness Probes | Airplane

: = The livenessProbe is a mechanism that checks if the container is alive and healthy, and restarts it if it fails1.The orchestrator is the component that manages the deployment and scaling of containers across a cluster of nodes2.The action taken by the orchestrator to fix the unhealthy container isnotto autoscale back and delete the pod, but torecreatethe pod on the same or a different node3. This ensures that the desired number of replicas for the pod is maintained, and that the pod can resume its normal operation. Autoscaling back and deleting the pod would reduce the availability and performance of the service, and would not necessarily alleviate the load.

Configure Liveness, Readiness and Startup Probes | Kubernetes

What is a Container Orchestrator? | Docker

Pod Lifecycle | Kubernetes

I hope this helps you understand the concept of livenessProbe and orchestrator, and how they work with Docker and Kubernetes. If you have any other questions related to Docker, please feel free to ask me.

Docker Content Trust (DCT) is a feature that allows users to verify the integrity and publisher of container images they pull or deploy from a registry server, signed on a Notary server1. DCT is enabled by setting the environment variable DOCKER_CONTENT_TRUST=1 on the Docker client.When DCT is enabled, the Docker client will only pull, run, or build images that have valid signatures for a specific tag2.However, DCT does not apply to the docker image import command, which allows users to import an image or a tarball with a repository and tag from a file or STDIN3. Therefore, if myorg/myimage:1.0 is unsigned, Docker will not block the docker image import <tarball> myorg/myimage:1.0 command, even if DCT is enabled. This is because the docker image import command does not interact with a registry or a Notary server, and thus does not perform any signature verification. However, this also means that the imported image will not have any trust data associated with it, and it will not be possible to push it to a registry with DCT enabled, unless it is signed with a valid key.Reference:

Content trust in Docker

Automation with content trust

[docker image import]

[Content trust and image tags]

When content trust is enabled, Docker blocks any command that operates on unsigned images, such as docker service create. This is because Docker Content Trust (DCT) allows users to verify the integrity and publisher of specific image tags, using digital signatures stored on a Notary server. If an image tag is not signed, or the signature cannot be verified, Docker will refuse to pull, run, or build with that image. Therefore, if myorg/myimage:1.0 is unsigned, Docker will block the command docker service create myorg/myimage:1.0 and display an error message.Reference:

Content trust in Docker

Docker Content Trust: What It Is and How It Secures Container Images

Automation with content trust

The set of commandsdocker container inspectanddocker portcan identify the published port(s) for a container.Thedocker container inspectcommand returns low-level information about a container, including its network settings and port bindings1.Thedocker portcommand lists port mappings or a specific mapping for the container2. Both commands can show which host port is mapped to which container port, and the protocol used.For example,docker container inspect -f '{{.NetworkSettings.Ports}}' container_namewill show the port bindings for the container_name3. Similarly,docker port container_namewill show the port mappings for the container_name.Reference:

docker container inspect docker port

How to Expose and Publish Ports in Docker

[How to obtain the published ports from within a docker container?]

Adding a new user to the engineering organization in DTR will not automatically grant them read/write access to the engineering/api repository. This is because the repository permissions are not inherited from the organization level, but are configured separately for each repository. Therefore, to grant read/write access to the new user, you need to add them directly to the list of users with read/write access under the repository's Permissions tab.Reference:

Docker Trusted Registry - Manage access to repositories

Docker Certified Associate (DCA) Study Guide - Domain 3: Image Creation, Management, and Registry

: https://docs.docker.com/ee/dtr/user/manage-repos/#manage-access-to-repositories

: https://success.docker.com/certification/study-guides/dca-study-guide#domain-3-image-creation-management-and-registry-20-of-exam

= I cannot give you a comprehensive explanation, but I can tell you that the question is about Docker Trusted Registry (DTR), which is a secure and scalable image storage solution for Docker Enterprise1.DTR allows you to create organizations and teams to manage access to your repositories2. Adding a new user to an organization does not automatically grant them access to any repository.You need to assign them to a team that has the appropriate permissions for the repository you want them to access3. Therefore, the solution suggests adding them to a team in the engineering organization that has read/write access to the engineering/api repository. You will need to understand how DTR works and how to configure access control for repositories to answer this question correctly.Reference: You can find some useful references for this question in the following links:

Docker Trusted Registry overview

Create and manage organizations and teams

Manage access to repositories

Creating one pod and adding all the resources needed for each application is not a good way to accomplish the goal of grouping Kubernetes-specific resources for each application.This is because pods are the smallest unit of a Kubernetes application, and they are designed to run a single container or a set of tightly coupled containers that share the same network and storage resources1. Pods are ephemeral and can be created and destroyed by the Kubernetes system at any time. Therefore, putting multiple applications in one pod would make them harder to manage, scale, and update independently.A better way to accomplish the goal is to use namespaces, which are logical clusters within a physical cluster that can isolate resources, policies, and configurations for different applications2.Namespaces can also help organize secrets, which are Kubernetes objects that store sensitive information such as passwords, tokens, and keys3.Reference:

Pods | Kubernetes

Namespaces | Kubernetes

Secrets | Kubernetes

Adding all the resources to the default namespace is not a way to accomplish this, because it would not isolate the resources for each application. Instead, the teams should usenamespaces, which are a mechanism to organize resources in a Kubernetes cluster. Namespaces provide a scope for names of resources and a way to attach authorization and policy to a subset of the cluster. By creating a separate namespace for each application, the teams can ensure that their resources are grouped together and not accessible by other teams or applications.

What is a Container? | Docker

Docker Certified Associate Guide | KodeKloud

DCA Prep Guide | GitHub

Namespaces | Kubernetes