DCA Exam Dumps : Docker Certified Associate (DCA) Exam

 In the context of a swarm mode cluster, an instance of the Docker engine participating in the swarm is indeed a node1. A node can be either a manager or a worker, depending on the role assigned by the swarm manager2. A manager node handles the orchestration and management of the swarm, while a worker node executes the tasks assigned by the manager2. A node can join or leave a swarm at any time, and the swarm manager will reconcile the desired state of the cluster accordingly1. References:

1: Swarm mode overview | Docker Docs

2: Manage nodes in a swarm | Docker Docs

= The command docker inspect nodes will not list all nodes in a swarm cluster from the command line. This command is invalid, as docker inspect requires one or more object names or IDs as arguments1. To list all nodes in a swarm cluster, you need to use the docker node ls command from a manager node2. This command will display the ID, hostname, status, availability, manager status, and engine version of each node in the swarm2. You can also use the -f or --filter flag to filter the nodes by various criteria, such as role, label, or name2. References:

1: docker inspect | Docker Docs

2: docker node ls | Docker Docs

The statement is correct. In the provided Docker Compose file, a health check is defined for the service “app”. It uses curl to perform a health check on the application every 10 seconds (as specified by the “interval” parameter). If it fails three times (as specified by the “retries” parameter), then the container is marked as unhealthy. A health check is a way of checking the health of a running container and applying actions based on the result1. It can be used to monitor the status of the service and restart the container if it becomes unhealthy2. References:

Compose file version 3 reference | Docker Docs

Docker Compose & Health Checks – Gabriel’s World