Practice Questions for Docker Certified Associate (DCA) Exam 🐳 — Set 1

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Grizzlybit

12 min readDec 25, 2020

Docker is quite the buzz tool nowadays, it is a tool that is making it easier to create, deploy, and run applications by using containers.

In today’s job market having Docker skills proves to be of immense importance and the Docker Certified Associate (DCA) exam is designed to validate that skillset with real-world questions designed by experienced Docker practitioners.

I believe you have stumbled on this post cause you have already begun your journey in becoming a Docker Certified Associate. To aid you in the process, I have compiled a few sample questions and answers below. This will definitely give you an idea of what format and kind of questions to expect during your examinations. Without further a-do, get cracking 😉

What is the command to set DNS server for all Docker containers?

Options are :

dockerd --dns-update IP_ADDRESS
dockerd --set-dns IP_ADDRESS
dockerd --dns-server IP_ADDRESS
dockerd --dns IP_ADDRESS

Answer : dockerd --dns IP_ADDRESS

What is the correct order to backup Docker EE components?

Options are :

Backup DTR, UCP, and then Swarm
Backup Swarm, DTR, and then UCP
Backup Swarm, UCP, and then DTR
Backup UCP, Swarm, and then DTR

Answer: Backup Swarm, UCP, and then DTR

What is the docker command to backup the UCP?

Options are :

docker ucp backup
docker backup ucp
docker backup all
docker/ucp backup

Answer : docker/ucp backup

What is the docker command to add or update a published port?

Options are :

docker service update --publish-add
docker service update --publish-port
docker service set --add-port
docker service modify --add-update-port

Answer : docker service update --publish-add

What is the difference between UCP workers and managers?

Options are :

Ucp-agent service automatically starts serving UCP components and proxy service only on worker node.
Ucp-agent service automatically starts serving UCP components and proxy service only on manger node.
Ucp-agent service automatically starts serving all UCP components in manager node and only proxy service in worker node.
Ucp-agent service automatically starts serving UCP components in worker node, and only a proxy service in manager node.

Answer: Ucp-agent service automatically starts serving all UCP components in manager node and only proxy service in worker node.

Which of the below correct command that needs to be executed to sign an image before pushing it to the repository?

Options are :

export TRUST_DOCKER_IMAGE=1
export TRUST_DOCKER_CONTENT=1
export SIGN_DOCKER_IMAGE=1
export DOCKER_CONTENT_TRUST=1

Answer : export DOCKER_CONTENT_TRUST=1

Which of the below Dockerfile directive would set up the base image that can serve as our starting point for establishing a new image?

Options are :

FROM
BASE
ARG
START

Answer : FROM

Which of the following best describes the procedure for backing up the Universal Control Plane (UCP) metadata?

Options are :

Create an archive for all of the data under the /etc/docker/ucp directory.
Create an archive for all of the data under the /var/data/ucp directory.
Run a container from the ucp image with the backup command.
Run a container from the ucp image with the uninstall-ucp command.

Answer: Run a container from the ucp image with the backup command.

What is the docker command to setup a swarm?

Options are :

docker create swarm
docker init swarm
docker swarm init
docker swarm create

Answer : docker swarm init

What does the FROM directive do?

Options are :

It indicates the build location of where the image is.
It pulls a file from an external source into the image.
It sets a base image that can be used as a platform to begin builds.
It sets the working directory of containers ran using the image.

Answer: It sets a base image that can be used as a platform to begin builds.

Which of the following commands is correct if the container exits due to an error, which manifests as a non-zero exit code.

Options are :

docker run --restart unless-stopped nginx
docker run --restart no nginx
docker run --restart on-failure nginx
docker run --restart failure-only nginx

Answer : docker run --restart on-failure nginx

Which Docker edition would you choose for obtaining the latest Docker Engine updates?

Options are :

Docker Enterprise Edition (EE)
Docker Developer Edition (DE)
Docker Community Edition (CE)
Either Docker CE or Docker EE

Answer : Either Docker CE or Docker EE

Which of the following is not backed up when performing a Docker Trusted Registry (DTR) metadata backup?

Options are :

DTR Configurations
Repository metadata.
Docker images.
Role-based access control (RBAC) settings.

Answer : Docker images.

What is the endpoint that we can use to check the health of a single UCP manager node?

Options are :

https:///\_ heartbeat
https:///\_ping
https:///\_ health
https:/// \_status

Answer : https:///\_ping

What is the docker command to roll back to the previous version of a service?

Options are :

docker service --rollback
docker service --rollback-version
docker service update --rollback
docker service update --rollback-version

Answer : docker service update --rollback

What are the two types of UCP client bundles?

Options are :

Admin user certificate bundles and user certificate bundles.
Docker CLI bundles and Docker web Ui bundles.
Docker UCP Client bundles and DTR client bundles.
Ops client bundles and dev client bundles.

Answer: Admin user certificate bundles and user certificate bundles.

What is the docker command to display detailed information on one or more networks?

Options are :

docker inspect network
docker network display
docker network inspect
docker network status

Answer : docker network inspect

What is the docker command to create a container with custom DNS server(s)?

Options are :

docker container create --cusom-dns=IP_ADDRESS
docker container create --set-dns=IP_ADDRESS
docker container create --dns=IP_ADDRESS
docker container create --add-dns=IP_ADDRESS

Answer : docker container create --dns=IP_ADDRESS

Which of the following commands will ensure that a container uses a maximum of 1 GB of active memory?

Options are :

docker run --memory-swap 2G nginx
docker run --memory 1G nginx
docker run --memory-swap 2G --memory-reservation 1G
docker run --memory-reservation 1G nginx

Answer : docker run --memory 1G nginx

Niels has an application that consists of multiple different containers that interact with one another. What should he use to manage this application in a Docker Swarm?

Options are :

Niels should use a service with multiple tasks.
Niels should use docker-compose .
Niels should use a stack .
Niels should use a task .

Answer: Niels should use a stack .

Danny wants to prevent Docker Swarm encryption keys from being stored insecurely on her swarm managers. How can he tackle enforcing a lock on the swarm cluster?

Options are :

Danny can locate the critical files after the installation and delete them.
Danny cannot do this because Docker does not offer this functionality.
The autolock feature must be turned on when the cluster is initialized and cannot be enabled after the fact.
Danny can use the --autolock=true flag with the docker swarm update command.

Answer: Danny can use the --autolock=true flag with the docker swarm update command.

Where can you get a repository URL for installing the Docker Enterprise Edition (EE)?

Options are :

Docker Hub
Docker Enterprise Hub
Docker Trusted Registry
Docker Marketplace

Answer: Docker Hub

What are the requirements to install Docker Trusted Registry (DTR)? (Select all that apply)

Options are :

Make sure the port 8080 and 8443 are open on the node
All nodes must be a worker node managed by Universal Control Plan
DTR can be installed on-premises or on a cloud provider
All nodes must have fixed hostname

Answer: All nodes must be a worker node managed by Universal Control Plan DTR can beinstalled on-premises or on a cloud provider All nodes must have fixed hostname

Which of the following is true about building docker images?

Options are :

Every Dockerfile can have only one FROM directive.
Only layers that have changed since the last build (and any following layers) are built.
Every layer of the image is re-built every time docker build is executed.
Every Dockerfile can have only one FROM directive.

Answer: Only layers that have changed since the last build (and any following layers) are built.

What would be the runtime working directory of a container built from the following Dockerfile?

FROM alpine

WORKDIR /a

WORKDIR /b

WORKDIR c

CMD pwd

Options are :

/c
/a
/b/c
/

Answer : /b/c

Which of the following tool to use to create users and teams?

Options are :

Universal Control Plane
Docker Machine
Docker compose
Docker Trusted Registry

Answer: Universal Control Plane

Where is the option to integrate Docker Enterprise with LDAP?

Options are :

Docker Trusted Registry
Docker Compose
Docker Machine
Universal Control Plane

Answer: Universal Control Plane

What is the docker command to find the current logging driver for a running container?

Options are :

docker info
docker config
docker inspect
docker status

Answer : docker inspect

Describe what the RUN directive does.

Options are :

The RUN directive sets the default command for the image.
The RUN directive executes a command on the host when building an image.
The RUN directive executes a command and commits the resulting changed files as a new layer in the image.
The RUN directive automatically runs a command when a new container gets created.

Answer: The RUN directive executes a command and commits the resulting changed files asa new layer in the image.

Paul have some containerized software that needs to have a reference to the hostname of the node that the software is running on. Which of the following commands Paul will pass the node hostname as an environment variable into each task in a service?

Options are :

docker service create --env NODE_HOSTNAME="{{.Node.Hostname}}" nginx
docker service create -e NODE_HOSTNAME nginx
docker service create --env NODE_HOSTNAME="{{Hostname}}" nginx
docker service create --pass-node-hostname=true nginx

Answer : docker service create --env NODE_HOSTNAME="{{.Node.Hostname}}" nginx

Which of the below statements does not apply to the WORKDIR directive?

Options are :

It affects only the build and does not impact containers that run from the image.
It affects only the build and does not impact containers that run from the image.
It can use both absolute and relative paths.
It affects only the build and does not impact containers that run from the image.

Answer: It affects only the build and does not impact containers that run from the image.

Which of the following scenarios would still allow the quorum to have maintenance in a swarm cluster? (Choose two)

Options are :

A 3-node cluster with 1 node down.
A 3-node cluster with 2 nodes down
A 7-node cluster with 3 nodes down.
A 4-node cluster with 2 nodes down.

Answer: A 3-node cluster with 1 node down. A 7-node cluster with 3 nodes down.

Which of the following commands can we use to view detailed metadata about a container? (select two)

Options are :

docker metadata
docker inspect
docker container inspect
docker query

Answer : docker inspect docker container inspect

What does the EXPOSE directive do?

Options are :

It causes the container to listen on a port.
It documents ports intended for publishing at the time of running a container.
It automatically publishes ports when running a container.
It makes a container’s port accessible externally.

Answer: It documents ports intended for publishing at the time of running a container.

Which of the following statements truly applies to the ENV directive?

Options are :

It sets an environment variable on the host while the container is running
It sets environment variables that are only visible at the container runtime.
It sets environment variables that are made available in subsequent build steps and to containers at the runtime.
It sets environment variables that are only visible during later build steps

Answer: It sets environment variables that are made available in subsequent build steps and to containers at the runtime.

In Docker security, scan result is available in both UCP and DTR.?

Options are :

TRUE
FALSE

Answer: FALSE

What is the docker command to increase the number of replicas?

Options are :

docker service replica
docker service increase
docker service scale
docker service build

Answer : docker service scale

How to configure the default logging driver?

Options are :

Use --log-driver flag
Set the --log-driver option in the deamon.json file
Set the --log-driver option in the key.json file
Use --loging-driver --flag

Answer: Set the --log-driver option in the deamon.json file

What are the steps to perform to sign images in a way that UCP trusts them? (select all that apply)

Options are :

Delegate signing to the keys in your UCP client bundle
Initialize trust metadata for the repository
Approve image sign on UCP
Configure Notary client

Answer: Delegate signing to the keys in your UCP client bundle Initialize trust metadata for the repository Configure Notary client

What is the docker command to backup the UCP?

Options are :

docker backup ucp
docker/ucp backup

Answer : docker/ucp backup

What are the requirements to install Docker Trusted Registry (DTR)? (Select all that apply)

Options are :

Make sure the port 8080 and 8443 are open on the node
All nodes must have a fixed hostname
DTR can be installed on-premises or on a cloud provider
All nodes must be a worker node managed by Universal Control Pla

Answer: All nodes must have a fixed hostname DTR can be installed on-premises or on a cloud provider All nodes must be a worker node managed by UCP

What is the docker command to setup a swarm?

Options are :

docker init swarm
docker create swarm
docker swarm create
docker swarm init

Answer : docker swarm init

What is the recommended approach to set storage driver?

Options are :

Set the “storage-driver” option in the daemon.json file
Use --storage-driver flag when running dockerd

Answer: Set the “storage-driver” option in the daemon.json file

What is the docker command to add a node to a swarm?

Options are :

docker swarm join
docker swarm create-node
docker join swarm
docker swarm add-node

Answer : docker swarm join

What is the correct order to upgrade a Docker cluster?

Options are :

Upgrade DTR, UCP, then engine and kernel
Upgrade engine and kernel, DTR, and then UCP
Upgrade engine and kernel, UCP, and then DTR
Upgrade UCP, DTR, then engine and kernel

Answer : Upgrade engine and kernel, UCP, and then DTR

What is the function of docker inspect command?

Options are :

To return low-level information on Docker objects
To display system-wide information
To manage Docker configs
To inspect changes to files or directories on a container’s filesystem

Answer: To return low-level information on Docker objects

What is the default format of docker inspect output?

Options are :

yaml
html
xml
json

Answer: json

What are the two types of docker swarm services?

Options are :

distributed and replicated services
replicated and local services
local and global services
replicated and global services

Answer: replicated and global services

What is the difference between a replicated and a global service?

Options are :

Number of identical tasks can be specified for a replicated service. There is no pre-specified number of tasks for global service
Replicated service can only be deployed on manager node. Global service can be deployed on both manager and worker node
Replicated service runs one task on every node. Global service runs multiple task on every node
Good candidates for replicated service are monitoring agents that you want to run on every node in the swarm. Good candidates for global service are http servers.

Answer: Number of identical tasks can be specified for a replicated service. There is no pre-specified number of tasks for global service

What is the docker command to add a network to a service?

Options are :

docker service modify --add-network
docker service update --network-add
docker service set --add-network
docker service add-network

Answer : docker service update --network-add

How is the ADD directive different from COPY ? (Choose two)

Options are :

The ADD directive can transfer a specific file between build stages.
The ADD directive can pull a file from an external URL.
The ADD directive can extract an archive into the image.
The ADD directive can transfer files over to a specific location inside the image.

Answer: The ADD directive can pull a file from an external URL. The ADD directive canextract an archive into the image.

What command would we use to locate the layered file system data for an image on a machine?

Options are :

docker image inspect
docker layer inspect
docker pull history
docker image layers

Answer : docker image inspect

Which of the following namespaces is not enabled by default?

Options are :

pid
uts
user
mnt

Answer : user

Which of the following docker command can be used to find out all the ports mapped? (select all that apply).

Options are :

docker inspect
docker network ls
docker ps
docker port

Answer : docker inspect docker ps docker port

You can monitor the status of UCP by using the web UI or the CLI?

Options are :

FALSE
TRUE

Answer : TRUE

Stay tuned to get further sets… 😉

Practice Questions for Docker Certified Associate (DCA) Exam 🐳 — Set 1

Written by Zubair Ahmed