DCA Question #21: Real Exam Question with Answer & Explanation

Question

Which of the following is true about overlay networks?

Options

• AOverlay networks are created only on the manager node that you created the overlay networking
• BOverlay networks are created on all cluster nodes when you create the overlay network.
• COverlay networks are first created on the manager nodes. Then they are created on the worker
• DOverlay networks are only created on the manager nodes.

Explanation

Overlay networks in a Docker Swarm are distributed across all nodes in the cluster to enable inter-container communication across different hosts.

Common mistakes.

• A. This is incorrect because overlay networks are designed for multi-host communication and are therefore distributed across the entire swarm, not confined to a single manager node.
• C. While manager nodes coordinate the creation, the overlay network is effectively available on all nodes simultaneously for container use, not in a staged fashion from managers to workers.
• D. This is incorrect because overlay networks are essential for worker nodes to host containers that need to communicate across the swarm, making them available on all nodes.

Concept tested. Docker Swarm overlay network distribution

Reference. https://docs.docker.com/network/overlay/

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