Exam Questions and Answers for DCA Study Guide Questions and Answers!
Docker Certified Associate (DCA) Exam Certification Sample Questions and Practice Exam
Topics of Docker Certified Associate Exam
Candidates should apprehend the examination topics before they begin of preparation. Our DCA exam dumps will include the following topics:
Lesson 01 - Introduction
- Containerization And Virtualization
- Images And Containers
- Docker Ecosystem
- Docker Architecture Container Format
- Docker Architecture InAction
- Understanding Docker Overview
Lesson 02 - Understanding Docker
- Deleting Containers
- Containers on Filesystem
- Multiple Containers
- Stats Inspect
- Deploy, Login, Exit Container
- List,Start, Stop Restart Containers
- Installation: CentOS
- Working with Containers Hostnames
Lesson 03 - Docker CE on Linux Platform
- Disconnect And Add Network
- None Network
- Exercise: Use Custom Networks
- Bridge Network
- Docker Networking
- Remove Networks
Lesson 04 - Docker Networking
- Persistent Storage
- Search and Pull Images from Docker Hub
- Manage Application Data
- Docker Storage Drivers
- External Storage
- Docker Volumes
- Build Image using Commit
- Selecting Storage Driver
- Docker Images: Recap
- Push Images to Docker Hub
- Docker Images CLI Commands: Contd
- Docker tmpfs Mounts
- Docker file Instructions
- Docker Images
- Build Image using Dockerfile
- Docker Images CLI Commands
Lesson 06 - Docker Storage and Volumes
- Compose Lab
- Compose Installation
- Case for Docker Compose
- Docker Compose
Lesson 07 - Docker Compose
- Maintain Swarm
- Secrets and Overlay Network
- Docker Swarm
- Docker Stack
- Managing Swarm Services
- Deploy Services to Swarm
- Create Swarm
- Updates to Services
Lesson 08 - Orchestration Docker Swarm
- LDAP with UCP
- Access Control
- Client Certificate Bundles
- Universal Control Plane
- Introduction to UCP
- External Certificates
Lesson 09 - Universal Control Plane
- Docker Trusted Registry
- Miscellaneous Topic with DTR
- Backup Swarm UCP DTR
- Introduction Deploy DTR
Lesson 10 - Docker Trusted Registry
- Security With MTLS
- Security Scanning
- Logs and Logging Drivers
- Docker Security Logs
- Docker Content Trust
NEW QUESTION # 17
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
Answer: A
Explanation:
= Control Groups (cgroups) are a feature of the Linux kernel that allow you to limit the access processes and containers have to system resources such as CPU, memory, disk I/O, network, and so on1. Control groups allow Docker Engine to share available hardware resources to containers and optionally enforce limits and constraints2. For example, you can use the docker run command to specify the CPU shares, memory limit, or network bandwidth for a container3. By using cgroups, you can ensure that each container gets the resources it needs and prevent resource starvation or overcommitment4. Reference:
Lab: Control Groups (cgroups) | dockerlabs
Runtime metrics | Docker Docs
Docker run reference | Docker Docs
Docker resource management via Cgroups and systemd
NEW QUESTION # 18
A company's security policy specifies that development and production containers must run on separate nodes in a given Swarm cluster.
Can this be used to schedule containers to meet the security policy requirements?
Solution: node taints
- A. Yes
- B. No
Answer: B
NEW QUESTION # 19
In Docker Trusted Registry, is this how a user can prevent an image, such as 'nginx:latest', from being overwritten by another user with push access to the repository?
Solution: Keep a backup copy of the image on another repository.
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
= Keeping a backup copy of the image on another repository is not how a user can prevent an image, such as
'nginx:latest', from being overwritten by another user with push access to the repository. This approach does not prevent the original image from being overwritten, it only provides a way to restore it from another source.
However, this may not be reliable or efficient, as the backup repository may not be in sync with the original one, or may not be accessible at all times. To prevent an image from being overwritten by another user, the user can use the DTR web UI to make the tag immutable1. This feature allows the user to lock a specific tag, so that no one can push a new image with the same tag to the repository. This ensures that the image is always consistent and secure1. References:
* Make a tag immutable | Docker Docs
NEW QUESTION # 20
Is this a type of Linux kernel namespace that provides container isolation?
Solution: Network
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
Network is a type of Linux kernel namespace that provides container isolation. Network namespaces isolate the system resources associated with networking, such as network interfaces, IP addresses, routing tables, firewall rules, etc. Each network namespace has its own virtual network stack, and processes in different network namespaces can communicate through virtual network devices or tunnels1. Network namespaces are used byDocker to create isolated networks for containers, and allow users to customize the network configuration and connectivity of each container2. References:
* network_namespaces(7) - Linux manual page
* Docker network overview | Docker Documentation
NEW QUESTION # 21
What behavior is expected when a service is created with the following command:
'docker service create --publish 8000:80 nginx'
- A. All nodes in the cluster will listen on port 80 and forward to port 8080 in the container.
- B. Only a single node in the cluster will listen on port 80 and forward to port 8080 in the container.
- C. All nodes in the cluster will listen on port 8080 and forward to port 80 in the container.
- D. Only a single node in the cluster will listen on port 8080 and forward to port 80 in the
container.
Answer: C
NEW QUESTION # 22
Is this a Linux kernel namespace that is disabled by default and must be enabled at Docker engine runtime to be used?
Solution: mnt
- A. Yes
- B. No
Answer: B
Explanation:
The mnt namespace is not disabled by default and does not need to be enabled at Docker engine runtime to be used. The mnt namespace is one of the six Linux kernel namespaces that Docker uses to isolate containers from the host system1. The mnt namespace allows a container to have its own set of mounted filesystems and root directories, which are different from the host's2. This means that a container can access only the files and directories that are mounted inside its namespace, and not the ones that are mounted on the host or other containers. The mnt namespace is created automatically when a container is started, and it is destroyed when the container stops3.
:
Isolate containers with a user namespace | Docker Docs
The mnt namespace - Docker Cookbook - Second Edition
Container security fundamentals part 2: Isolation & namespaces
mnt is not a Linux kernel namespace that is disabled by default and must be enabled at Docker engine runtime to be used. According to the official documentation, mnt is one of the namespaces that are enabled by default when using namespaces for isolation.
NEW QUESTION # 23
Will this command mount the host's '/data' directory to the ubuntu container in read-only mode?
Solution: 'docker run -v /data:/mydata --mode readonly ubuntu'
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
This command will not mount the host's '/data' directory to the ubuntu container in read-only mode, because it has an incorrect option for making the volume read-only. According to the official documentation, the correct command should be:
docker run -v /data:/mydata:ro ubuntu
The incorrect option is:
The --mode flag does not exist and should be replaced by a :ro suffix to make the volume read-only.
References: https://docs.docker.com/engine/reference/commandline/run/#mount-volume-v-read-only
https://docs.docker.com/storage/volumes/#use-a-read-only-volume
NEW QUESTION # 24
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 '--cpu-quota' flag to '1.3' on one container and '2,4' on the other container.
- C. Set the '--cpuset-cpus' flag of the 'dockerd' process to the value 'even-spread'
- D. Set the '--cpuset-cpus' flag to '.5' on both containers
Answer: D
NEW QUESTION # 25
During development of an application meant to be orchestrated by Kubernetes, you want to mount the /data directory on your laptop into a container.
Will this strategy successfully accomplish this?
Solution: Add a volume to the pod that sets hostPath.path: /data, and then mount this volume into the pod's containers as desired.
- A. Yes
- B. No
Answer: B
Explanation:
The solution will not work because a hostPath volume mounts a file or directory from the host node's filesystem into the pod, not from the laptop1. The host node is the VM or machine where the pod is scheduled to run, not the machine where the kubectl commands are executed. Therefore, the /data directory on the laptop will not be accessible to the pod unless it is also present on the host node. A better solution would be to use a persistent volume that can be accessed from any node in the cluster, such as NFS, AWS EBS, or Azure Disk2. Reference:
1: Volumes | Kubernetes
2: Persistent Volumes | Kubernetes
NEW QUESTION # 26
You add a new user to the engineering organization in DTR.
Will this action grant them read/write access to the engineering/api repository?
Solution: Add them to a team in the engineering organization that has read/write access to the engineering/api repository.
- A. Yes
- B. No
Answer: B
Explanation:
= I cannot give you a comprehensive explanation, but I can tell you that the question is about Docker Trusted Registry (DTR), which is a secure and scalable image storagesolution for Docker Enterprise1. DTR allows you to create organizations and teams to manage access to your repositories2. Adding a new user to an organization does not automatically grant them access to any repository. You need to assign them to a team that has the appropriate permissions for the repository you want them to access3. Therefore, the solution suggests adding them to a team in the engineering organization that has read/write access to the engineering/api repository. You will need to understand how DTR works and how to configure access control for repositories to answer this question correctly. Reference: You can find some useful references for this question in the following links:
Docker Trusted Registry overview
Create and manage organizations and teams
Manage access to repositories
NEW QUESTION # 27
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 omit-stopped redis'
- B. 'docker run -d --restart unless-stopped redis'
- C. 'docker run -d --failure omit-stopped redis'
- D. 'docker run -d --restart-policy unless-stopped redis'
Answer: D
NEW QUESTION # 28
What is one way of directly transferring a Docker Image from one Docker host in another?
- A. 'docker push' the image to the IP address of the target host.
- B. 'docker commit' to save the image outside of the Docker filesystem. Then transfer the file over to the target host and 'docker start' to start the container again.
- C. There is no way of directly transferring Docker images between hosts. A Docker Registry must be used ad an intermediary.
- D. 'docker save' the image to save it as TAR file and copy it over to the target host. Then use 'docker load' to un-TAR the image back as a Docker image.
Answer: D
NEW QUESTION # 29
Does this describe the role of Control Groups (cgroups) when used with a Docker container?
Solution: isolation between resources used by containers
- A. Yes
- B. No
Answer: A
Explanation:
Control Groups (cgroups) are a Linux kernel feature that allow you to limit, modify, or allocate resources as needed1. Docker uses cgroups to isolate the resources used by containers, such as CPU, memory, disk I/O, network, etc2. This means that each container can have its own set of resource limits and constraints, and that the containers cannot interfere with each other or with the host system2. This improves the security, performance, and reliability of the containers and the system as a whole. References:
* Lab: Control Groups (cgroups) | dockerlabs
* Docker run reference | Docker Docs
NEW QUESTION # 30
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, use it to populate a volume associated with the pod, and mount that file from the volume to the appropriate container and path.
- A. Yes
- B. No
Answer: B
Explanation:
= Mounting the configuration file directly into the appropriate pod and container using the
.spec.containers.configMounts key is not a valid way to provide a configuration file to a container at runtime. The .spec.containers.configMounts key does not exist in the Kubernetes API1. The correct way to provide a configuration file to a container at runtime is to use a ConfigMap2. A ConfigMap is a Kubernetes object that stores configuration data as key-value pairs. You can create a ConfigMap from a file, and then mount the ConfigMap as a volume into the pod and container. The configuration file will be available as a file in the specified mount path3. Alternatively, you can also use environment variables to pass configuration data to a container from a ConfigMap4. References:
* PodSpec v1 core
* Configure a Pod to Use a ConfigMap
* Populate a Volume with data stored in a ConfigMap
* Define Container Environment Variables Using ConfigMap Data
NEW QUESTION # 31
You want to provide a configuration file to a container at runtime. Does this set of Kubernetes tools and steps accomplish this?
Solution: Mount the configuration file directly into the appropriate pod and container using the .spec.containers.configMounts key.
- A. Yes
- B. No
Answer: B
Explanation:
The solution given is not a valid way to provide a configuration file to a container at runtime using Kubernetes tools and steps. The reason is that there is no such key as .spec.containers.configMounts in the PodSpec. The correct key to use is .spec.containers.volumeMounts, which specifies the volumes to mount into the container's filesystem1. To use a ConfigMap as a volume source, one needs to create a ConfigMap object that contains the configuration file as a key-value pair, and then reference it in the .spec.volumes section of the PodSpec2. A ConfigMap is a Kubernetes API object that lets you store configuration data for other objects to use3. For example, to provide a nginx.conf file to a nginx container, one can do the following steps:
Create a ConfigMap from the nginx.conf file:
kubectl create configmap nginx-config --from-file=nginx.conf
Create a Pod that mounts the ConfigMap as a volume and uses it as the configuration file for the nginx container:
apiVersion: v1
kind: Pod
metadata:
name: nginx-pod
spec:
containers:
- name: nginx
image: nginx
volumeMounts:
- name: config-volume
mountPath: /etc/nginx/nginx.conf
subPath: nginx.conf
volumes:
- name: config-volume
configMap:
name: nginx-config
:
Configure a Pod to Use a Volume for Storage | Kubernetes
Configure a Pod to Use a ConfigMap | Kubernetes
ConfigMaps | Kubernetes
NEW QUESTION # 32
Will this command display a list of volumes for a specific container?
Solution. 'docker container logs nginx -volumes'
- A. Yes
- B. No
Answer: B
Explanation:
The command docker container logs nginx -volumes will not display a list of volumes for a specific container. The docker container logs command shows the logs of a container, which are usually the standard output and standard error of the main process running in the container1. The -volumes flag is not a valid option for this command, and will result in an error message2. To display a list of volumes for a specific container, you can use the docker inspect command with a filter option, such as docker inspect -f '{{ .Mounts
}}' nginx3. This will show the source, destination, mode, type, and propagation of each volume mounted in the container4. References: docker container logs, docker container logs nginx -volumes, docker inspect, docker inspect -f '{{ .Mounts }}' nginx
NEW QUESTION # 33
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
Answer: B
Explanation:
= The command docker service create -name dns-cache -p 53:53 -udp dns-cache will not create a swarm service that only listens on port 53 using the UDP protocol. The reason is that the command has several syntax errors and invalid options. The correct command to create a swarm service that only listens on port 53 using the UDP protocol is docker service create --name dns-cache --publish published=53,target=53,protocol=udp dns-cache12. The command docker service create -name dns-cache -p 53:53 -udp dns-cache has the following problems:
* The option -name is not a valid option for docker service create. The valid option for specifying the service name is --name3.
* The option -p is not a valid option for docker service create. The valid option for publishing a port for a service is --publish1.
* The option -udp is not a valid option for docker service create. The valid option for specifying the protocol for a published port is protocol within the --publish option1.
* The argument 53:53 is not a valid argument for docker service create. The argument for docker service create should be the image name for the service, such as dns-cache3. The source and target of the published port should be specified in the --publish option, separated by a comma1.
Therefore, the command docker service create -name dns-cache -p 53:53 -udp dns-cache will not work as intended, and will likely produce an error message or an unexpected result. References:
* Use swarm mode routing mesh
* Manage swarm service networks
* docker service create
NEW QUESTION # 34
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
Answer: B
Explanation:
The command kubectl get deployment api will only show the status of the deployment object, such as the number of replicas, available pods, and updated pods1. It will not display the events table for the deployment, which contains information about the creation, scaling, and updating of the deployment and its pods2. To see the events table for the deployment, you need to use the kubectl describe deployment api command, which will show the details of the deployment object, including the events3. Alternatively, you can use the kubectl get events --field-selector involvedObject.name=api command, which will filter the events by the name of the involved object4. References:
* Kubectl: Get Deployments - Kubernetes - ShellHacks
* Events in Kubernetes | Kubernetes
* kubectl Cheat Sheet | Kubernetes
* kubernetes - kubectl get events only for a pod - Stack Overflow
NEW QUESTION # 35
Will this command list all nodes in a swarm cluster from the command line?
Solution: 'docker swarm nodes'
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
Using 'docker swarm nodes' does not list all nodes in a swarm cluster from the command line. The docker swarm command is used to initialize or join a swarm, or manage swarm options. It does not have a nodes subcommand. To list all nodes in a swarm cluster from the command line, you need to use 'docker node ls'.
References: https://docs.docker.com/engine/reference/commandline/swarm/,
https://docs.docker.com/engine/reference/commandline/node_ls/
NEW QUESTION # 36
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
Answer: B
NEW QUESTION # 37
Will this action upgrade Docker Engine CE to Docker Engine EE?
Solution.Run docker engine activate.
- A. Yes
- B. No
Answer: A
Explanation:
Running docker engine activate will upgrade Docker Engine CE to Docker Engine EE. This is a feature that allows you to switch from the Community Edition to the Enterprise Edition without reinstalling Docker or losing any data. You need to have a valid license file and a subscription to Docker EE to use this feature1. Docker EE is a premium version of Docker CE that offers additional features, such as security scanning, image management, and certified plugins23. Reference:
Upgrade Docker Engine | Docker Docs
What is the exact difference between Docker EE (Enterprise Edition), Docker CE (Community Edition) and Docker (Custom Support) - Stack Overflow Docker Community Edition or Docker Enterprise Edition - Docker | BoxBoat
NEW QUESTION # 38
Which of the following commands will ensure that overlay traffic between service tasks is encrypted?
- A. docker service create --network <network-name> --encrypted <service-name>
- B. docker service create --network <network-name> --secure <service-name>
- C. docker network create -d overlay --secure <network-name>
- D. docker network create -d overlay -o encrypted=true <network-name>
Answer: D
NEW QUESTION # 39
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
Answer: A
Explanation:
Explanation
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. References:
https://docs.docker.com/engine/swarm/key-concepts/#nodes-and-services,
https://docs.docker.com/engine/swarm/how-swarm-mode-works/nodes/
NEW QUESTION # 40
......
Docker Certified Associate (DCA) exam is a certification exam that validates one's skills and knowledge in using Docker containers. DCA exam is designed for individuals who have a good understanding of Docker fundamentals and are looking to advance their skills in this area. The DCA exam is an industry-recognized certification that demonstrates one's expertise in Docker technologies and practices.
Docker Certified Associate (DCA) certification exam is a globally recognized certification that validates the knowledge and skills of professionals in using Docker Enterprise Edition (EE) and Docker Community Edition (CE) for containerization. Docker Certified Associate (DCA) Exam certification is designed to help IT professionals and developers to showcase their proficiency in Docker technologies and to demonstrate their ability to use Docker to build, ship, and run containerized applications.
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