DCA Exam Dumps - Docker Certified Associate (DCA) Exam

To configure a Docker container to export container logs to a logging solution such as Splunk, you need to set the log-driver and log-opt keys to values for the logging solution in the daemon.json file. This will enable the Splunk logging driver, which sends container logs to HTTP Event Collector in Splunk Enterprise and Splunk Cloud1. You can also use the command-line flags --log-driver and --log-opt with docker run to use the Splunk driver for a specific container1. References:

• Splunk logging driver | Docker Docs
• Collecting docker logs and stats with Splunk | Splunk
• How to send Docker containers logs to Splunk?
• Splunk Logging Driver for Docker | Splunk

To trust a self-signed certificate from a Docker Trusted Registry (DTR), you need to place the certificate in the appropriate location on all cluster nodes and restart the Docker daemon. There are two possible locations for the certificate, depending on your OS and Docker version1:

•/etc/docker/certs.d/dtr.example.com/ca.crt: This is the preferred location for Linux systems and Docker versions 1.13 and higher. This directory is scanned by Docker for certificates and keys for each registry domain2.

•Your OS certificate path: This is the fallback location for other OSes and Docker versions. You need to find the certificate store for your OS and copy the certificate there. You also need to trust the certificate system-wide, which may require additional steps depending on your OS3.

The other options are not correct because:

•Passing '-trust-certificate ca.crt to the Docker client is not a valid option. There is no such flag for the Docker client4.

•Placing the certificate in ‘/etc/docker/dtr/dtr.example.com.crt’ is not a valid location. The certificate should be in the /etc/docker/certs.d directory, not the /etc/docker/dtr directory1.

•Passing – insecure-registry to the Docker client is not a recommended option. This flag disables the TLS verification for the registry, which makes the communication insecure and vulnerable to attacks.

References:

•Use self-signed certificates | Docker Docs

•Test an insecure registry | Docker Docs

•Add TLS certificates as a trusted root authority to the host OS | Docker Docs

•docker | Docker Docs

•[Deploy a registry server | Docker Docs]

The action will not upgrade Docker Engine CE to Docker Engine EE. Disabling the Docker service via chkconfig or systemctl will only stop the Docker daemon from running, but it will not change the version or edition of the Docker engine1. To upgrade Docker Engine CE to Docker Engine EE, you need to follow these steps2:

• Download your Docker Enterprise license from the Docker Store).
• Install the docker-ee package from the Docker repository.
• Restart the Docker service and verify the version and edition. References: Start or stop the Docker daemon), How to upgrade Docker 18.09 Community Edition to Docker Enterprise 18.09)

 The command docker network create -d overlay -o encrypted=true  will ensure that overlay traffic between service tasks is encrypted. This command creates an overlay network with the encryption option enabled, which means that Docker will create IPSEC tunnels between all the nodes where tasks are scheduled for services attached to the overlay network. These tunnels use the AES algorithm in GCM mode and manager nodes automatically rotate the keys every 12 hours1. This way, the data exchanged between containers on different nodes on the overlay network is secured. References:

• Overlay network driver

Tagging the image with ‘nginx:immutable’ 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. Tagging the image with ‘nginx:immutable’ will only create a new tag for the image, but it will not prevent the original tag from being overwritten. To prevent an image tag from being overwritten in Docker Trusted Registry, the user can use the DTR web UI to make the tag immutable1. This will prevent anyone from pushing a new image with the same tag, even if they have push access to the repository1. Alternatively, the user can also use the DTR API to make the tag immutable2. References: Prevent tags from being overwritten), DTR API reference)

 The command docker inspect http will not enable you to view the list of historical tasks for the service. The docker inspect command returns low-level information on Docker objects, such as containers, images, networks, or volumes1. It does not work on services, which are higher-level objects that define the desired state of a set of tasks2. To view the list of historical tasks for a service, you need to use the docker service ps command, which shows the current and previous states of each task, as well as the node, error, and ports3. References:

• docker inspect | Docker Docs
• Services | Docker Docs
• docker service ps | Docker Docs

= (Please check the official Docker site for the comprehensive explanation) References: (Some possible references from the web search results are)

• 25 Free Questions on Docker Certified Associate Exam - Whizlabs
• Practice Questions for Docker Certified Associate (DCA) Exam - Medium
• Practice Exams (3 Sets) - Docker Certified Associate (DCA) - Udemy
• Docker Certified Associate Practice Exam | +600 exam quizz - Udemy
• Docker Certified Associate DCA Practice Exam | UPDATED 2023 - Udemy

I hope this helps you in your exam preparation. Good luck! 😊

 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.

References:

• 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.

References: https://docs.docker.com/engine/security/userns-remap/#user-namespace-known-limitations