Docker Containerization Docker Swarm and Orchestration 3

Question 1

What is the purpose of the '--publish mode=host' option when creating a Swarm service?

Accepted Answer

It binds the port directly on the host without using the routing mesh

Answer

Using mode=host bypasses the Swarm routing mesh and binds the port directly to the host node, meaning only nodes running the task accept traffic on that port.

Question 2

Which Raft consensus requirement must be met for a Swarm cluster to remain operational?

Accepted Answer

A majority (quorum) of manager nodes must be reachable

Answer

Swarm uses the Raft protocol, which requires a quorum — more than half of managers — to elect a leader and process cluster changes.

Question 3

What does the 'docker service rollback <service>' command do?

Accepted Answer

Reverts the service to its previous configuration before the last update

Answer

The rollback command reverts a service to the configuration it had before the most recent 'docker service update' was applied.

Question 4

In a Docker Swarm stack file, what does the 'deploy.mode: global' setting accomplish?

Accepted Answer

Runs exactly one task on every node in the cluster

Answer

Global mode ensures one instance of the service runs on every node in the swarm, useful for agents and monitoring daemons.

Question 5

What network driver does Docker Swarm use by default for multi-host service communication?

Accepted Answer

overlay

Answer

Overlay networks span multiple Docker hosts and are the default driver for Swarm services that need to communicate across nodes.

Docker Practice Test

Docker Practice Test

Docker Containerization Docker Swarm and Orchestration 3