Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 81:

  Which statement is true about DTR garbage collection?

  A. Garbage collection removes unreferenced image layers from DTR's backend storage.
  B. Garbage collection removes exited containers from cluster nodes.
  C. Garbage collection removes DTR images that are older than a configurable of days D. Garbage collection removes unused volumes from cluster nodes
  A. Garbage collection removes unreferenced image layers from DTR's backend storage.

• Question 82:

  An application image runs in multiple environments, and each environment uses different certificates and ports, what is the best practice to deploy the containers?

  A. Create a Dockerfile for each environment, specifying ports and ENV variables for certificates.
  B. Create a Dockerfile for each environment, specifying ports and Docker secrets for certificates.
  C. Create images that contain the specific configuration for every environment.
  D. Create a config file for each environment.
  D. Create a config file for each environment.

• Question 83:

  Two development teams in your organization use Kubernetes and want to deploy their applications while ensuring that Kubernetes-specific resources, such as secrets, are grouped together for each application.

  Is this a way to accomplish this?

  Solution: Add all the resources to the default namespace.

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  This is not a way to accomplish this, because adding all the resources to the default namespace is not a good practice for isolating applications in Kubernetes. According to the official documentation, namespaces are used to group resources into logical units that correspond to different projects, teams, or environments. Using namespaces can help avoid naming collisions and enforce resource quotas and access policies.

• Question 84:

  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: docker logs

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Using docker logs does not configure a Docker container to export container logs to the logging solution. The docker logs command shows information logged by a running container, such as standard output and standard error streams. It does not send or export container logs to any external service.

• Question 85:

  Does this describe the role of Control Groups (cgroups) when used with a Docker container? Solution: user authorization to the Docker API

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  This does not describe the role of Control Groups (cgroups) when used with a Docker container, because user authorization to the Docker API is not related to cgroups. According to the official documentation, cgroups are a Linux kernel feature that limits and isolates the resource usage of a group of processes, such as CPU, memory, disk I/O, network, etc. Docker can use cgroups to share available hardware resources to containers and optionally enforce limits and constraints.

• Question 86:

  Which of the following commands starts a Redis container and configures it to always restart unless it is explicitly stopped or Docker is restarted?

  A. 'docker run -d --restart-policy unless-stopped redis'
  B. 'docker run -d --restart omit-stopped redis'
  C. 'docker run -d --restart unless-stopped redis'
  D. 'docker run -d --failure omit-stopped redis'
  C. 'docker run -d --restart unless-stopped redis'

• Question 87:

  A docker service 'web' is running with a scale factor of 1 (replicas = 1).

  Bob intends to use the command 'docker service update --replicas=3 web'.

  Alice intends to use the command 'docker service scale web=3'.

  How do the outcomes oft these two commands differ?

  A. Bob's command results in an error. Alice's command updates the number of replicas of the 'web' service to 3.
  B. Bob's command only updates the service definition, but no new replicas are started. Alice's command results in the actual scaling up of the 'web' service.
  C. Bob's command updates the number of replicas of the 'web' service to 3. Alice's command results in an error.
  D. Both Bob's and Alice's commands result in exactly the same outcome, which is 3 instances of the 'web' service.
  D. Both Bob's and Alice's commands result in exactly the same outcome, which is 3 instances of the 'web' service.

• Question 88:

  Does this describe the role of Control Groups (cgroups) when used with a Docker container? Solution: accounting and limiting of resources

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This does describe the role of Control Groups (cgroups) when used with a Docker container, because accounting and limiting of resources is one of the main functions of cgroups. According to the official documentation, cgroups are a Linux kernel feature that limits and isolates the resource usage of a group of processes, such as CPU, memory, disk I/O, network, etc. Docker can use cgroups to share available hardware resources to containers and optionally enforce limits and constraints.

• Question 89:

  An application image runs in multiple environments, with each environment using different certificates and ports.

  Is this a way to provision configuration to containers at runtime?

  Solution: Provision a Docker config object for each environment.

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Provisioning a Docker config object for each environment is a way to provision configuration to containers at runtime. A Docker config object is a file that contains configuration data for an application or service. It can be created using the docker config create command and then attached to a service using the --config flag of the docker service create or update command. This allows different configurations to be applied to different environments without changing the image or the code of the application.

• Question 90:

  Will this command list all nodes in a swarm cluster from the command line? Solution: 'docker swarm nodes'

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  This command does not list all nodes in a swarm cluster from the command line. The docker swarm command manages swarm operations, such as initializing or joining a swarm, updating the swarm configuration, etc. It does not show information about nodes or services. To list all nodes in a swarm cluster from the command line, you need to use docker node ls command. This command shows information about all the nodes that are part of the swarm, such as their ID, hostname, status, availability, etc.