Which monitoring type focuses on node metrics and kubelet performance without application-level data?

The correct choice is focused on infrastructure-only monitoring, which targets the collection and analysis of node metrics and kubelet performance specifically in environments such as Kubernetes. This type of monitoring is essential for operations teams that need to ensure the underlying infrastructure is running smoothly without delving into the details of the applications themselves.

Infrastructure-only monitoring collects data on resource utilization, system health, and various performance metrics of nodes and containers managed by kubelets, providing a comprehensive view of how the infrastructure is performing. This includes metrics like CPU usage, memory consumption, disk IO, and network throughput, which are critical for maintaining service availability and optimizing performance at the infrastructure level.

The other types of monitoring mentioned do not align with this focus. Service monitoring typically encompasses tracking the performance of specific services and understanding their interactions, which includes application context. Application-only monitoring is concerned with application performance, user experiences, and application metrics, rather than infrastructure metrics. Custom namespace monitoring, while potentially useful in specific scenarios, would focus on tracking resources and services within a defined namespace and may still incorporate elements relevant to application performance. Thus, these alternatives do not specifically address the focus solely on node and kubelet performance.