Docker DCA Exam Actual Questions

The statement is not entirely correct. In Kubernetes, a service of type ClusterIP routes traffic sent to its IP address to the pods selected by its label selector1. However, the port to which the traffic is routed in the pod is determined by the targetPort specified in the service definition1. If targetPort is not specified, it defaults to being the same as the port field1. In the provided YAML snippet, there is no targetPort specified for port 80, so we cannot confirm that the traffic will be routed to port 8080 in the pod. Therefore, without additional information about the pod configuration, we cannot verify the provided solution statement1.

Docker allows the use of insecure registries through a specific configuration in the Docker daemon. By listing the insecure registries in the 'daemon.json' configuration file under the 'insecure-registries' key, Docker can interact with these registries even without a trusted TLS certificate1. This is particularly useful when setting up a private Docker registry1. However, it's important to note that this configuration bypasses the security provided by TLS, and should be used with caution1.

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 as interval, timeout, and retries. In this case, the health checks are not set to test five seconds apart but rather ten seconds apart (interval: 10s). The retries: 3 indicates that if the health check fails, Docker will try three times before considering the container unhealthy1.

While creating a Dockerfile for each environment is a possible solution, it is not the most efficient or scalable way to provision configuration to containers at runtime. Docker provides several mechanisms to inject configuration into containers at runtime, such as environment variables, command line arguments, Docker secrets for sensitive data, or even configuration files mounted as volumes. These methods allow the same Docker image to be used across multiple environments, promoting immutability and consistency across your deployments. Creating a separate Dockerfile for each environment would mean maintaining multiple versions of the Dockerfile, which could lead to inconsistencies and is generally not a recommended practice.

Yes, the docker port command can be used to identify the published ports for a running container. It shows the mapping between the host ports and the container's exposed ports. The docker network inspect command can also provide information about the network settings of the container, including port mappings. However, it's important to note that docker network inspect requires the network's name or ID as an argument, not the container's. Therefore, to get the network details of a specific container, you would first need to identify the network the container is connected to. These commands, when used appropriately, can help you identify the published ports for a container.