Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 111:

  You configure a local Docker engine to enforce content trust by setting the environment variable

  DOCKER_CONTENT_TRUST=1.

  If myorg/myimage: 1.0 is unsigned, does Docker block this command?

  Solution: docker image import myorg/myimage:1.0

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Docker does not block this command, because docker image import does not verify content trust by default. According to the official documentation, docker image import creates an image from an existing tarball file and does not interact with any registry or sign any content.

• Question 112:

  Is this a way to configure the Docker engine to use a registry without a trusted TLS certificate? Solution: Pass the '--insecure-registry' flag to the daemon at run time.

  A. Yes
  B. No
  A. Yes

• Question 113:

  Can this set of commands identify the published port(s) for a container? Solution: docker container inspect', 'docker port'

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This set of commands can identify the published port(s) for a container, because docker container inspect can show the port mappings for a container and docker port can list the public port that is NAT-ed to the private port. According to the official documentation, these commands can be used to find the exposed ports for a container.

• Question 114:

  Is this a function of UCP?

  Solution: enforces the deployment of signed images to the cluster

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Enforcing the deployment of signed images to the cluster is a function of UCP. UCP supports image signing and verification using Docker Content Trust, which is a feature that provides the ability to use digital signatures for data sent to and received from remote Docker registries. UCP allows you to configure a policy that requires all images deployed to the cluster to be signed by a trusted authority. This way, you can ensure that only authorized and verified images are used in your applications.

• Question 115:

  Is this statement correct?

  Solution: A Dockerfile provides instructions for building a Docker image

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This statement is correct. A Dockerfile provides instructions for building a Docker image. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using docker build, you can create an automated build that executes several command-line instructions in succession.

• Question 116:

  What is the difference between a resource limit and a resource reservation when scheduling services?

  A. A resource limit and a resource reservation can be used interchangeably.
  B. A resource limit is a soft limit for your service, while a reservation is hard limit and the docker engine will do its best to keep your service at the limit.
  C. A resource limit is used to find a host with adequate resources for scheduling a hard limit for your service, while a reservation is hard limit for your service.
  D. A resource limit is hard limit for your service, while a reservation is used to find a host with adequate resources for scheduling. Correct
  A. A resource limit and a resource reservation can be used interchangeably.

• Question 117:

  Will this configuration achieve fault tolerance for managers in a swarm? Solution: only two managers, one active and one passive.

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  This configuration will not achieve fault tolerance for managers in a swarm, because having only two managers creates a risk of losing quorum if one manager fails or becomes unavailable. According to the official documentation, having two managers also does not provide any benefits over having one manager, since both managers must be available for any management operations.

• Question 118:

  Your organization has a centralized logging solution, such as Splunk.

  Will this configure a Docker container to export container logs to the logging solution?

  Solution. Set the log-driver-and log-opt keys to values for the logging solution (Splunk) in the daemon.json file.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Setting the log-driver and log-opt keys to values for the logging solution (Splunk) in the daemon.json file does configure a Docker container to export container logs to the logging solution. The daemon.json file is a configuration file for the Docker daemon that allows you to specify various options, such as the default logging driver and logging options. The log-driver key sets the default logging driver for all containers, unless overridden by the --log-driver option when creating or running a container. The log-opt key sets the default logging options for all containers, unless overridden by the --log-opt option when creating or running a container. To use Splunk as the default logging driver, you can set the log-driver key to splunk and provide the Splunk URL, token, and other options using the log-opt key.

• Question 119:

  In the context of a swarm mode cluster, does this describe a node? Solution: a virtual machine participating in the swarm

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  A virtual machine participating in the swarm is a node in the context of a swarm mode cluster. A node is an instance of the Docker engine participating in the swarm. A node can be either a physical machine or a virtual machine. Nodes are either managers or workers. Managers maintain cluster state and manage cluster tasks. Workers execute tasks assigned by managers.

• Question 120:

  Will this command display a list of volumes for a specific container?

  Solution: `docker container inspect nginx'

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Using docker container inspect nginx does display a list of volumes for a specific container. The docker container inspect command shows low-level information about one or more containers in JSON format. This information includes various details about the container's configuration, state, network settings, mounts, etc. To display a list of volumes for a specific container, you can either look at the Mounts section in the JSON output or use --format `{{ .Mounts }}' to filter out only that section.