Certified Kubernetes Application Developer (CKAD) Practice Test

When you need to ensure that only one instance of a Pod is running on a Node, a DaemonSet is the appropriate choice. A DaemonSet assures that a single Pod runs on each Node in the cluster, and when you want just one instance per Node, it will ensure that each Node has that single Pod representation.

DaemonSets are particularly useful for running background services on Nodes, such as logging or monitoring agents, where you require a Pod to be present on each Node. Although the total number of Pods might increase as new Nodes are added, it guarantees that one Pod per Node is maintained.

The other options serve different purposes. A ReplicaSet manages a specified number of identical Pods but does not limit their hosting to a single instance per Node. StatefulSets are designed for stateful applications where the identity and storage associated with Pods is critical, focusing on maintaining a specific sequence and identity rather than limiting them to one per Node. Deployments are primarily used for managing and rolling out updates to replicated applications and do not inherently guarantee single-instance limitation on Nodes.