Docker Certified Associate Flashcards

If the docker engine does not serve as a manager node for the docker swarm, how may overlay networks be created?

Answer: True

In the event that the docker engine is a component of a swarm, overlay networks may exist. Therefore, being a manager node in a swarm is a requirement for creating an overlay network. The following problem occurs when we attempt to create overlay networks from a non-manager node: ubuntu@ip-10-0-1-11:~$ docker network create -d overlay test-network Daemon error message: Unable to build a multi-host network from a worker node. Please build the network starting with a manager node.

Which of the subsequent claims is true? Select exactly two statements.

Answer: Image is a collection of immutable layers whereas container is a running instance of an image.

There are immutable layers in an image. A container is a live copy of an image. When several containers are launched from a single picture, only one copy of the image is stored in memory. In order to handle its local modifications, each container has a separate Read and Write layer.

Which of the following parameters would allow you to SSH into an active "nginx" Docker container?

Answer: docker exec -it nginx /bin/sh

"docker exec -it nginx /bin/sh" will construct a TTY-equipped interactive session that is tied to the STDIN.

On AWS, you are creating a brand-new Docker Swarm. You must make sure that neither the Security Group Rules nor the Network Access Control List are blocking traffic between hosts. Which of the following statements accurately describes every port that needs to be open between Docker hosts?

Answer: TCP/2377, TCP/7946, and UDP/7946

TCP port 2377 for cluster management communications TCP and UDP port 7946 for communication among nodes

Which of the commands can be used to view an IPv4 network's subnet?

Answer: docker network inspect

"docker network inspect" is an authorized command to examine a certain network

How can John launch a container that utilizes the json-file log driver when he has configured his Docker daemon to use the syslog log driver by default?

Answer: By using “--log-driver json-file” along with docker run

The correct flag is `--log-driver`, so `docker run --log-driver json-file` overrides the daemon's default syslog driver for that single container. `--logger` is not a valid option, and `--log-opt` only sets driver-specific options (key=value pairs), not the driver itself.

What commands are valid to run global services in Docker swarm?

Answer: docker service create --mode global

Global services are created with `docker service create --mode global`, which runs one task on every node in the swarm. There is no `--global` flag, and `docker swarm create` is not a valid command—swarm is initialized with `docker swarm init`, while services are managed with `docker service`.