100% PASS RATE Docker Certified Associate DCA Certified Exam DUMP with 169 Questions
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NEW QUESTION # 40
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. label constraints
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
Label constraints can be used to schedule containers to meet the security policy requirements. Label constraints are expressions that match node labels to service labels. Node labels are key-value pairs that can be attached to nodes to identify them by certain characteristics, such as role, environment, region, etc. Service labels are key-value pairs that can be attached to services to specify scheduling preferences or requirements, such as node.role == manager or environment != production. Label constraints can be used with the
--constraint flag when creating or updating a service to ensure that the service's containers are scheduled on nodes that match the specified criteria. References:
https://docs.docker.com/engine/swarm/services/#specify-service-constraints,
https://docs.docker.com/engine/swarm/manage-nodes/#add-or-remove-label-metadata
NEW QUESTION # 41
Will this command mount the host's '/data' directory to the ubuntu container in read-only mode?
Solution: 'docker run --add-volume /data /mydata -read-only ubuntu'
- A. Yes
- B. No
Answer: B
NEW QUESTION # 42
The Kubernetes yaml shown below describes a clusterIP service.
Is this a correct statement about how this service routes requests?
Solution: Traffic sent to the IP of any pod with the label app: nginx on port 8080 will be forwarded to port 80 in that pod.
- A. Yes
- B. No
Answer: A
NEW QUESTION # 43
In the context of a swarm mode cluster, does this describe a node?
Solution.an instance of the Docker CLI connected to the swarm
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
The statement does not describe a node in the context of a swarm mode cluster. A node is a physical or virtual machine running Docker Engine 1.12 or later in swarm mode1. An instance of the Docker CLI connected to the swarm is not a node, but a client that can interact with the swarm through the Docker API2. The Docker CLI can be used to create a swarm, join nodes to a swarm, deploy services to a swarm, and manage swarm behavior3. References: How nodes work), Docker CLI), Swarm mode overview)
NEW QUESTION # 44
Will this action upgrade Docker Engine CE to Docker Engine EE?
Solution.Run docker engine activate.
- A. Yes
- B. No
Answer: A
Explanation:
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. References:
* 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 # 45
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: Create one pod and add all the resources needed for each application
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
Creating one pod and adding all the resources needed for each application is not a good way to accomplish the goal of grouping Kubernetes-specific resources for each application. This is because pods are the smallest unit of a Kubernetes application, and they are designed to run a single container or a set of tightly coupled containers that share the same network and storage resources1. Pods are ephemeral and can be created and destroyed by the Kubernetes system at any time. Therefore, putting multiple applications in one pod would make them harder to manage, scale, and update independently. A better way to accomplish the goal is to use namespaces, which are logicalclusters within a physical cluster that can isolate resources, policies, and configurations for different applications2. Namespaces can also help organize secrets, which are Kubernetes objects that store sensitive information such as passwords, tokens, and keys3. References:
* Pods | Kubernetes
* Namespaces | Kubernetes
* Secrets | Kubernetes
NEW QUESTION # 46
The Kubernetes yaml shown below describes a networkPolicy.
Will the networkPolicy BLOCK this trafftc?
Solution. a request issued from a pod bearing the tier: backend label, to a podbearing the tier: frontend label
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
The networkPolicy will block the traffic from a pod bearing the tier: backend label, to a pod bearing the tier:
frontend label. The networkPolicy specifies that only pods with the tier: frontend label can access the pods with the app: guestbook-api and tier: backend labels on port 801. Any other traffic to the backend pods will be denied by default2. Therefore, a request issued from a pod bearing the tier: backend label, to a pod bearing the tier: frontend label will be blocked by the networkPolicy. References: Connect a Frontend to a Backend Using Services), Network Policies)
NEW QUESTION # 47
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: A
Explanation:
Explanation
This action will grant them read/write access to the engineering/api repository, because adding them to a team in the engineering organization that has read/write access to the engineering/api repository is another way to grant permissions to a user in DTR. According to the official documentation, this is an example of using teams and organizations for managing permissions.
References: https://docs.docker.com/ee/dtr/user/manage-repos/permission-levels/
NEW QUESTION # 48
Will this command mount the host's '/data' directory to the ubuntu container in read-only mode?
Solution: 'docker run --add-volume /data /mydata -read-only ubuntu'
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
n: = Using the DTR web UI to make all tags in the repository immutable is not a good way to prevent an image, such as 'nginx:latest', from being overwritten by another user with push access to the repository. This is because making all tags immutable would prevent any updates to the images in the repository, which may not be desirable for some use cases. For example, if a user wants to push a new version of 'nginx:latest' with a security patch, they would not be able to do so if the tag is immutable. A better way to prevent an image from being overwritten by another user is to use the DTR web UI to create a promotion policy that restricts who can push to a specific tag or repository1. Alternatively, the user can also use the DTR API to create a webhook that triggers a custom action when an image is pushed to a repository2. References:
* Prevent tags from being overwritten | Docker Docs
* Create webhooks | Docker Docs
NEW QUESTION # 49
Will this Linux kernel facility limit a Docker container's access to host resources, such as CPU or memory?
Solution: cgroups
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
Using cgroups does limit a Docker container's access to host resources, such as CPU or memory. Cgroups are a Linux kernel feature that allow grouping and managing processes and their resource consumption. They can be used to limit, account, and isolate the resource usage of a container, such as CPU time, memory, disk I/O, network bandwidth, etc. References: https://docs.docker.com/config/containers/resource_constraints/,
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/index.html
NEW QUESTION # 50
Will this sequence of steps completely delete an image from disk in the Docker Trusted Registry?
Solution: Delete the image and run garbage collection on the Docker Trusted Registry.
- A. Yes
- B. No
Answer: B
NEW QUESTION # 51
One of several containers in a pod is marked as unhealthy after failing its livenessProbe many times. Is this the action taken by the orchestrator to fix the unhealthy container?
Solution: The controller managing the pod is autoscaled back to delete the unhealthy pod and alleviate load.
- A. Yes
- B. No
Answer: A
NEW QUESTION # 52
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
Answer: B
Explanation:
Explanation
= The role of Control Groups (cgroups) when used with a Docker container is not user authorization to the Docker API. 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, RAM, IOPS and network1. Cgroups enable Docker to share available hardware resources to containers and optionally enforce limits and constraints2. User authorization to the Docker API is a different concept that involves granting permissions to users or groups to perform certain actions on the Docker daemon, such as creating, running, or stopping containers3.
References:
* Lab: Control Groups (cgroups) | dockerlabs
* Runtime metrics | Docker Docs
* Authorize users to access the Docker API | Docker Docs
I hope this helps you understand the role of cgroups and how they work with Docker containers. If you have any other questions related to Docker, please feel free to ask me.
NEW QUESTION # 53
Can this set of commands identify the published port(s) for a container?
Solution: docker container inspect', 'docker port'
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
The set of commands docker container inspect and docker port can identify the published port(s) for a container. The docker container inspect command returns low-level information about a container, including its network settings and port bindings1. The docker port command lists port mappings or a specific mapping for the container2. Both commands can show which host port is mapped to which container port, and the protocol used. For example, docker container inspect -f '{{.NetworkSettings.Ports}}' container_name will show the port bindings for the container_name3. Similarly, docker port container_name will show the port mappings for the container_name. References:
* docker container inspect
* docker port
* How to Expose and Publish Ports in Docker
* [How to obtain the published ports from within a docker container?]
NEW QUESTION # 54
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: resource reservation
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
Resource reservation cannot be used to schedule containers to meet the security policy requirements, because resource reservation only affects the available resources on a node and does not restrict which containers can run on which nodes. According to the official documentation, resource reservation is used to ensure that a service has enough resources to run.
References: https://docs.docker.com/engine/swarm/services/#reserve-memory-or-cpus-for-a-service
NEW QUESTION # 55
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 -service udp dns-cache'
- A. Yes
- B. No
Answer: B
Explanation:
Explanation
This command does not create a swarm service that only listens on port 53 using the UDP protocol, because it has several syntax errors and missing options. According to the official documentation, the correct command should be:
docker service create --name dns-cache -p 53:53/udp --mode global dns-cache The errors and missing options are:
The --name flag is missing a dash (-).
The -p flag is missing the /udp suffix to specify the protocol.
The --service flag does not exist and should be replaced by --mode to specify the service mode.
The global option should follow the --mode flag to indicate that one task should run on each node.
References:
https://docs.docker.com/engine/reference/commandline/service_create/#publish-service-ports-externally-to-the-s
https://docs.docker.com/engine/reference/commandline/service_create/#specify-service-mode-mode
https://docs.docker.com/engine/reference/commandline/service_create/#options
NEW QUESTION # 56
Are these conditions sufficient for Kubernetes to dynamically provision a persistentVolume, assuming there are no limitations on the amount and type of available external storage?
Solution: A persistentVolumeClaim is created that specifies a pre-defined storageClass.
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
= The conditions are sufficient for Kubernetes to dynamically provision a persistentVolume, because a storageClass defines the provisioner and parameters for creating a volume on-demand. A persistentVolumeClaim that specifies a storageClass triggers the dynamic provisioning process, and Kubernetes will automatically create and bind a persistentVolume that matches the request. This eliminates the need for manual intervention by cluster administrators to provision storage volumes. References:
* Dynamic Volume Provisioning | Kubernetes
* Persistent volumes and dynamic provisioning | Google Kubernetes Engine ...
* Dynamic Provisioning and Storage Classes in Kubernetes
NEW QUESTION # 57
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:
Explanation
= The command 'docker service create -name dns-cache -p 53:53/udp dns-cache' is not correct and will not create a swarm service that only listens on port 53 using the UDP protocol. There are two errors in the command:
* The option -name should be --name with two dashes, otherwise it will be interpreted as a short option -n followed by an argument ame1.
* The option -p or --publish will publish the service port to the host port, which means the service will be reachable from outside the swarm2. To create a service that only listens on the internal network, you need to use the --publish-add option with the mode=ingress flag3.
The correct command should be:
docker service create --name dns-cache --publish-add mode=ingress,target=53,published=53,protocol=udp dns-cache References:
* docker service create | Docker Docs
* Publish ports on the host | Docker Docs
* Publish a port for a service | Docker Docs
NEW QUESTION # 58
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:
Explanation
Using kubectl get deployment api does not display the events table for this object. The kubectl get command shows basic information about one or more resources, such as their name, age, status, etc. It does not show the events table, which is a list of events that occurred on the resource, such as creation, update, scaling, etc. To see the events table for this object, you need to use kubectl describe deployment api. References:
https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#get,
https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#describe
NEW QUESTION # 59
After creating a new service named 'http', you notice that the new service is not registering as healthy. How do
you view the list of historical tasks for that service by using the command line?
- A. 'docker inspect http'
- B. 'docker service ps http'
- C. 'docker service inspect http'
- D. 'docker ps http'
Answer: B
NEW QUESTION # 60
Are these conditions sufficient for Kubernetes to dynamically provision a persistentVolume, assuming there are no limitations on the amount and type of available external storage?
Solution: A default storageClass is specified, and subsequently a persistentVolumeClaim is created.
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
= The conditions are sufficient for Kubernetes to dynamically provision a persistentVolume, because they include a default storageClass and a persistentVolumeClaim. A storageClass defines which provisioner should be used and what parameters should be passed to that provisioner when dynamic provisioning is invoked. A persistentVolumeClaim requests a specific size, access mode, and storageClass for the persistentVolume. If a persistentVolume that satisfies the claim exists or can be provisioned, the persistentVolumeClaim is bound to that persistentVolume. A default storageClass means that any persistentVolumeClaim that does not specify a storageClass will use the default one. Therefore, the conditions in the question are enough to enable dynamic provisioning of storage volumes on-demand. References:
* Dynamic Volume Provisioning | Kubernetes
* Persistent volumes and dynamic provisioning | Google Kubernetes Engine ...
NEW QUESTION # 61
The Kubernetes yaml shown below describes a networkPolicy.
Will the networkPolicy BLOCK this traffic?
Solution: a request issued from a pod bearing the tier: backend label, to a pod bearing the tier: frontend label
- A. Yes
- B. No
Answer: A
Explanation:
Explanation
The networkPolicy will block this traffic because it only allows ingress traffic from pods that have the tier: api label. Pods that have the tier: backend label do not match this selector and are therefore denied access to pods that have the tier: frontend label.
References:
https://kubernetes.io/docs/concepts/services-networking/network-policies/#the-networkpolicy-resource
NEW QUESTION # 62
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: A
Explanation:
Explanation
This command creates a swarm service that only listens on port 53 using the UDP protocol, because the -p flag specifies the published port and target port separated by a colon (:) and followed by the protocol name (/udp).
According to the official documentation, this is an example of using the short version of the publish option to expose a port for a service.
References:
https://docs.docker.com/engine/reference/commandline/service_create/#publish-service-ports-externally-to-the-s
NEW QUESTION # 63
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