Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 121:

  Is this a Linux kernel namespace that is disabled by default and must be enabled at Docker engine runtime to be used? Solution: pid

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  pid is not a Linux kernel namespace that is disabled by default and must be enabled at Docker engine runtime to be used. pid is a Linux kernel namespace that provides process isolation for containers. It ensures that processes in one container cannot see or signal processes in another container or on the host system. pid is enabled by default for Docker containers and does not require any special flag or option to be used. However, you can disable pid isolation for a container by using --pid host option when creating or running a container. This option connects the container to the host's pid namespace and allows the container to see and signal processes on the host system.

• Question 122:

  Is this the purpose of Docker Content Trust? Solution: Verify and encrypt Docker registry TLS.

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Verifying and encrypting Docker registry TLS is not the purpose of Docker Content Trust. According to the official documentation, this is done by using HTTPS or self- signed certificates for secure communication with a registry.

• Question 123:

  Is this a function of UCP?

  Solution: scans images to detect any security vulnerability

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Scanning images to detect any security vulnerability is not a function of UCP. UCP stands for Universal Control Plane, which is a web-based user interface for managing Docker Enterprise clusters and applications. UCP does not provide image scanning capabilities, but it integrates with Docker Trusted Registry (DTR), which does offer image scanning as part of its security features.

• Question 124:

  What is the purpose of multi-stage builds?

  A. Better logical separation of Dockerfile instructions for better readability
  B. Optimizing images by copying artifacts selectively from previous stages
  C. Better caching when building Docker images
  D. Faster image builds by allowing parallel execution of Docker builds
  B. Optimizing images by copying artifacts selectively from previous stages

• Question 125:

  Does this describe the role of Control Groups (cgroups) when used with a Docker container? Solution: role-based access control to clustered resources

  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 role-based access control to clustered resources 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 126:

  You created a new service named 'http' and discover it is not registering as healthy. Will this command enable you to view the list of historical tasks for this service? Solution: 'docker inspect http'

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Using docker inspect http does not enable you to view the list of historical tasks for this service. The docker inspect command shows low-level information about one or more objects, such as containers, images, networks, etc. It does not show information about services or tasks. To view the list of historical tasks for this service, you need to use docker service ps http --no-trunc.

• Question 127:

  What is the recommended way to configure the daemon flags and environment variables for your Docker daemon in a platform independent way?

  A. Set the configuration options using the ENV variable
  B. Set the configuration options in '/etc/docker/daemon.json'
  C. Set the configuration DOCKER_OPTS in '/etc/default/docker'
  D. Using 'docker config' to set the configuration options.
  B. Set the configuration options in '/etc/docker/daemon.json'

• Question 128:

  Is this a type of Linux kernel namespace that provides container isolation? Solution: Authentication

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  Authentication is not a type of Linux kernel namespace that provides container isolation. 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, there is no authentication namespace in Linux. The types of namespaces that exist are mount (mnt), process ID (pid), network (net), interprocess communication (ipc), user ID (user), control group (cgroup), time (time), and user namespace (uts).

• Question 129:

  Is this an advantage of multi-stage builds?

  Solution: optimizes Images by copying artifacts selectively from previous stages

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  Optimizing images by copying artifacts selectively from previous stages 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 build. You can selectively copy artifacts from one stage to another, leaving behind everything you don't want in the final image. This reduces the size and complexity of your images, and improves security and performance.

• Question 130:

  Will this command display a list of volumes for a specific container? Solution: docker volume logs nginx --containers'

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  This command will not display a list of volumes for a specific container, because it uses docker volume inspect with an image name instead of a volume name. According to the official documentation, docker volume inspect requires one or

  more volume names as arguments and will show detailed information about the volumes, not the containers that use them.

  References: https://docs.docker.com/engine/reference/commandline/volume_inspect/