The verified answer in the PDF is A (HPA), and that aligns with the common Kubernetes meaning of “adjust resources for an application” by scaling replicas. The Horizontal Pod Autoscaler automatically changes the number of Pod replicas for a workload (typically a Deployment) based on observed metrics such as CPU utilization, memory (in some configurations), or custom/external metrics. By increasing replicas under load, the application gains more total CPU/memory capacity available across Pods; by decreasing replicas when load drops, it reduces resource consumption and cost.
It’s important to distinguish what each mechanism adjusts:
HPA adjusts replica count (horizontal scaling).
VPA adjusts Pod resource requests/limits (vertical scaling), which is literally “amount of CPU/memory per pod,” but it often requires restarts to apply changes depending on mode.
Cluster Autoscaler adjusts the number of nodes in the cluster, not application replicas.
KEDA is event-driven autoscaling that often drives HPA behavior using external event sources (queues, streams), but it’s not the primary built-in mechanism referenced in many foundational Kubernetes questions.
Given the wording and the provided answer key, the intended interpretation is: “automatically adjust the resources available to the application” by scaling out/in the number of replicas. That’s exactly HPA’s role. For example, if CPU utilization exceeds a target (say 60%), HPA computes a higher desired replica count and updates the workload. The Deployment then creates more Pods, distributing load and increasing available compute.
So, within this question set, the verified correct choice is A (Horizontal Pod Autoscaler).
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