Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 141:

  A host machine has four CPUs available and two running containers. The sysadmin would like to assign two CPUs to each container. Which of the following commands achieves this?

  A. Set the '--cpuset-cpu's flag to '1.3' on one container and '2.4' on the other container.
  B. Set the '--cpuset-cpus' flag to '.5' on both containers
  C. Set the '--cpuset-cpus' flag of the 'dockerd' process to the value 'even-spread'
  D. Set the '--cpu-quota' flag to '1.3' on one container and '2,4' on the other container.
  B. Set the '--cpuset-cpus' flag to '.5' on both containers

• Question 142:

  You are troubleshooting a Kubernetes deployment called api, and want to see the events table for this object.

  Does this command display it?

  Solution: kubectl get deployment api

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Using kubectl get deployment api does not display the events table for this object. The kubectl get command shows basic information about one or more resources, such as their name, age, status, etc. It does not show the events table, which is a list of events that occurred on the resource, such as creation, update, scaling, etc. To see the events table for this object, you need to use kubectl describe deployment api.

• Question 143:

  Will this Linux kernel facility limit a Docker container's access to host resources, such as CPU or memory? Solution: seccomp

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Using seccomp does not limit a Docker container's access to host resources, such as CPU or memory. Seccomp is a Linux kernel facility that allows filtering system calls made by a process. It can be used to enhance the security and isolation of a container by restricting its access to certain system calls. However, it does not affect the resource allocation or consumption of a container.

• Question 144:

  You want to provide a configuration file to a container at runtime. Does this set of Kubernetes tools and steps accomplish this?

  Solution: Turn the configuration file into a configMap object and mount it directly into the appropriate pod and container using the .spec.containers.configMounts key.

  A. Yes
  B. No
  B. No

• Question 145:

  Is this an advantage of multi-stage builds?

  Solution: better logical separation of Dockerfile instructions for increased readability

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Better logical separation of Dockerfile instructions for increased readability is not an advantage of multi-stage builds. Multi-stage builds are a feature that allows you to use multiple FROM statements in your Dockerfile. Each FROM statement begins a new stage of the build. You can selectively copy artifacts from one stage to another, leaving behind everything you don't want in the final image. The main advantage of multi-stage builds is that they allow you to reduce the size of your final image by only including the essential components and dependencies. Another advantage of multi-stage builds is that they allow you to optimize the build cache by grouping similar instructions in each stage. Better logical separation of Dockerfile instructions for increased readability is not an inherent advantage of multi-stage builds, as it depends on how you write and organize your Dockerfile.

• Question 146:

  A persistentVolumeClaim (PVC) is created with the specification storageClass: "", and size requirements that cannot be satisfied by any existing persistentVolume. Is this an action Kubernetes takes in this situation?

  Solution: The PVC remains unbound until a persistentVolume that matches all requirements of the PVC becomes available.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  The PVC remains unbound until a persistentVolume that matches all requirements of the PVC becomes available is an action Kubernetes takes in this situation. A persistentVolumeClaim (PVC) is a request for storage by a user. A PVC specifies the desired size, access modes, and storage class of the storage. A persistentVolume (PV) is a piece of storage in the cluster that has been provisioned by an administrator. A PV has a lifecycle independent of any individual pod that uses it. A PVC is automatically bound to a suitable PV based on its requirements. If no PV exists that matches the PVC, and dynamic provisioning is not enabled, then the PVC remains unbound indefinitely until a matching PV is created.

• Question 147:

  Will this action upgrade Docker Engine CE to Docker Engine EE?

  Solution: Uninstall 'docker-ce' package before installing 'docker-ee' package.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Uninstalling `docker-ce' package before installing `docker-ee' package does upgrade Docker Engine CE to Docker Engine EE. Docker Engine CE is the free and open source edition of Docker Engine, while Docker Engine EE is the enterprise-ready edition that includes additional features and support. To upgrade from CE to EE, you need to uninstall the `docker-ce' package and its dependencies, and then install the `docker-ee' package from the Docker repository.

• Question 148:

  Will this Linux kernel facility limit a Docker container's access to host resources, such as CPU or memory? Solution: namespaces

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Using namespaces does not limit a Docker container's access to host resources, such as CPU or memory. Namespaces are a Linux kernel feature that provide isolation and virtualization of system resources for processes. They can be used to create isolated environments for containers that have their own view of system resources, such as process IDs, user IDs, network interfaces, etc. However, they do not control how much resources a container can use or access.

• Question 149:

  Does this command create a swarm service that only listens on port 53 using the UDP protocol? Solution: 'docker service create --name dns-cache -p 53:53/udp dns-cache'

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This command creates a swarm service that only listens on port 53 using the UDP protocol, because the -p flag specifies the published port and target port separated by a colon (:) and followed by the protocol name (/udp). According to the official documentation, this is an example of using the short version of the publish option to expose a port for a service.

• Question 150:

  Is this a function of UCP?

  Solution: image role-based access control

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Image role-based access control is a function of UCP. UCP allows you to define granular permissions for users and teams to access images stored in DTR. You can assign different roles to users and teams, such as read-only, read-write, or admin, for each image repository or namespace. This way, you can control who can pull or push images to your registry. References: https://docs.docker.com/ee/ucp/