DCA Exam Dumps : Docker Certified Associate (DCA) Exam

= The command docker service create --network --secure will not ensure that overlay traffic between service tasks is encrypted. This is because the --secure option is not a valid option for the docker service create command1. To ensure that overlay traffic between service tasks is encrypted, you need to use the --opt encrypted option when creating the overlay network with the docker network create command2. For example, to create an encrypted overlay network named my-net, you can use the following command:

docker network create --driver overlay --opt encrypted my-net

Then, you can use the --network my-net option when creating the service with the docker service create command3. For example, to create a service named my-service using the nginx image and the my-net network, you can use the following command:

docker service create --name my-service --network my-net nginx

docker service create | Docker Docs

Use overlay networks | Docker Docs

Create a service | Docker Docs

= 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

The statement is incorrect about the health check definition based on the Docker Compose file provided. According to the Docker documentation, a health check can be specified in a Dockerfile or a Docker Compose file to tell Docker how to test a container to check that it is still working. This can be done with options such asinterval,timeout, andretries. In this case, the health checks are not set to test five seconds apart but rather ten seconds apart (interval: 10s).Theretries: 3indicates that if the health check fails, Docker will try three times before considering the container unhealthy1.