DCA Docker Swarm & Orchestration

Question 1

What command initializes a Docker Swarm and makes the current node a manager?

Accepted Answer

docker swarm init

Answer

docker swarm create

Answer

docker cluster init

Answer

docker swarm start

Question 2

Which TCP port does Docker Swarm use by default for manager-to-manager communication (Raft consensus)?

Accepted Answer

2377

Answer

2375

Answer

2376

Answer

7946

Question 3

In Docker Swarm, what is a 'task'?

Accepted Answer

A running container instance that is part of a service

Answer

A scheduled cron job running periodically in the cluster

Answer

A configuration file defining service parameters

Answer

A health check performed on service containers

Question 4

What command retrieves the join token needed to add a worker node to an existing Swarm?

Accepted Answer

docker swarm join-token worker

Answer

docker swarm token --worker

Answer

docker node add --token worker

Answer

docker swarm worker-token

Question 5

What is the key difference between 'replicated' and 'global' service modes in Docker Swarm?

Accepted Answer

Replicated services run a specified number of task copies; global services run exactly one task on every available node

Answer

Replicated services run on specific nodes; global services run on all nodes

Answer

Replicated services use the ingress network; global services use host networking

Answer

Replicated services support rolling updates; global services do not

Question 6

Which command lists all nodes currently participating in a Docker Swarm?

Accepted Answer

docker node ls

Answer

docker swarm nodes

Answer

docker cluster list

Answer

docker ps --swarm

Question 7

How do you scale a replicated service named 'web' to 5 replicas in Docker Swarm?

Accepted Answer

docker service scale web=5

Answer

docker service scale web 5

Answer

docker service update --replicas 5 web

Answer

docker swarm scale --service web --replicas 5