DCA Exam Dumps - Docker Certified Associate Questions and Answers

   = Using network connect to access the container on the bridge network does not accomplish creating a container that is reachable from its host’s network. The network connect command connects a container to an existing network, but it does not expose the container’s ports to the host1. The bridge network is the default network that Docker creates for containers, and it provides isolation from the host network2. To create a container that is reachable from its host’s network, you need to use the host network driver, which disables network isolation and uses the host’s network stack directly3. Alternatively, you can use the port mapping feature to publish specific ports of the container to the host4. References:

docker network connect | Docker Docs

Bridge network driver | Docker Docs

Host network driver | Docker Docs

Publish ports on the host | Docker Docs

 Capabilities are a Linux kernel feature that allows processes to perform some privileged operations without having the full power of the root user1. Docker uses capabilities to limit the access of containers to host resources, such as CPU or memory2. By default, Docker drops all capabilities except those needed for the container to function properly, using a whitelist approach3. This reduces the risk of a container compromising the host system or other containers. You can also add or remove capabilities to or from a container at runtime, using the --cap-add or --cap-drop options of the docker run command4. This gives you more control over the security and functionality of your containers. References:

Capabilities | dockerlabs

Docker run reference | Docker Docs

Docker Capabilities and no-new-privileges

Runtime privilege and Linux capabilities | Docker Docs

Using either EXPOSE or -publish to access the container on the bridge network will not accomplish the goal of creating a container that is reachable from its host’s network. EXPOSE is a way of documenting which ports a container listens on, but it does not open any ports to the host1. -publish (or -p) is a way of mapping a host port to a container port, but it does not change the network mode of the container2. By default, Docker containers use the bridge network, which isolates them from the host network3. To create a container that is reachable from its host’s network, you need to usethe --network host option when running the container4. This will make the container share the host’s network stack and have the same IP address as the host4. References:

1: Difference Between “expose” and “publish” in Docker | Baeldung on Ops

2: Deploy services to a swarm | Docker Docs

3: Bridge network | Docker Docs

4: Host network | Docker Docs

 In the context of a swarm mode cluster, an instance of the Docker engine participating in the swarm is indeed a node1. A node can be either a manager or a worker, depending on the role assigned by the swarm manager2. A manager node handles the orchestration and management of the swarm, while a worker node executes the tasks assigned by the manager2. A node can join or leave a swarm at any time, and the swarm manager will reconcile the desired state of the cluster accordingly1. References:

1: Swarm mode overview | Docker Docs

2: Manage nodes in a swarm | Docker Docs

Image role-based access control is not a function of UCP. UCP has its own built-in authentication mechanism and integrates with LDAP services. It also has role-based access control (RBAC), so that you can control who can access and make changes to your cluster and applications1. However, image role-based access control is a feature of Docker Trusted Registry (DTR), which integrates with UCP and allows you to manage the images you use for your applications2. DTR lets you define granular permissions for images, such as who can push, pull, delete, or scan them3. References: Universal Control Plane overview), Docker Trusted Registry overview), Docker Access Control)

 Better caching when building Docker images is an advantage of multi-stage builds. Multi-stage builds allow you to use multiple FROM statements in your Dockerfile, each starting a new stage of the build1. This can help you improve the caching efficiency of your Docker images, as each stage can use its own cache layer2. For example, if you have a stage that installs dependencies and another stage that compiles your code, you can reuse the cached layer of the dependencies stage if they don’t change, and only rebuild the code stage if it changes2. This can save you time and bandwidth when building and pushing your images. References:

Multi-stage builds | Docker Docs

What Are Multi-Stage Docker Builds? - How-To Geek

= I cannot give you a comprehensive explanation, but I can tell you that the statement is not entirely correct. The health check definition in the Docker Compose file tests for app health 18 seconds apart, not 10 seconds apart. Additionally, if the test fails, the container will be restarted 3 times before it gets rescheduled, not 4 times. References:

Docker Associate Resources and guides: 1 and 2

Docker Compose health check documentation: 3

Docker health check documentation: 4

I hope this helps you prepare for your DCA exam. If you want to practice more questions, you can check out some of the online courses that offer practice exams, such as 5, 6, 7, 8, and 9. Good luck!????

Tagging the image with ‘nginx:immutable’ is not how a user can prevent an image, such as ‘nginx:latest’, from being overwritten by another user with push access to the repository.Tagging the image with ‘nginx:immutable’ will only create a new tag for the image, but it will not prevent the original tag from being overwritten. To prevent an image tag from being overwritten in Docker Trusted Registry, the user can use the DTR web UI to make the tag immutable1. This will prevent anyone from pushing a new image with the same tag, even if they have push access to the repository1. Alternatively, the user can also use the DTR API to make the tag immutable2. References: Prevent tags from being overwritten), DTR API reference)

The networkPolicy will block the traffic from a pod bearing the tier: backend label, to a pod bearing the tier: frontend label. The networkPolicy specifies that only pods with the tier: frontend label can access the pods with the app: guestbook-api and tier: backend labels on port 801. Any other traffic to the backend pods will be denied by default2. Therefore, a request issued from a pod bearing the tier: backend label, to a pod bearing the tier: frontend label will be blocked by the networkPolicy. References: Connect a Frontend to a Backend Using Services), Network Policies)