The command docker service create --name myweb --network webnet --mode global nginx creates a Docker Swarm service named myweb using the nginx image. The --mode global option specifies that the service should run exactly once on each node in the Swarm cluster.
* Global Mode: When a service is created in global mode, Docker Swarm ensures that exactly one instance of the service runs on each node. This is useful for tasks that should run on all nodes, such as monitoring agents.
The other options are incorrect:
* A: It does not run exactly one time in the Swarm; it runs once on each node.
* C: This describes the replicated mode, not the global mode.
* D: The service runs on all nodes, not just those providing the webnet network.
* E: There is no network type called global.
References:
* Docker Documentation - Service Create
* Docker Documentation - Swarm Services