Which implementation in Kubernetes limits deployment to a single cluster?

The implementation that limits deployment to a single cluster is Node Affinity. Node Affinity is a set of rules used by Kubernetes to control which nodes your pods can be scheduled on, based on labels and conditions set on the nodes. When a pod is configured with Node Affinity, it ensures that the pod will only be deployed on nodes that meet certain criteria within the same Kubernetes cluster, thereby restricting deployment to that particular cluster.

In contrast, Pod Affinity pertains to how pods can be scheduled in relation to other pods, determining their placement based on labels; it doesn't restrict the deployment to a single cluster. The Cluster Autoscaler focuses on automatically adjusting the size of your cluster based on the current resource demand but doesn't impose restrictions on deployment across multiple clusters. Service Mesh refers to a dedicated infrastructure layer for managing service-to-service communication, which also does not limit deployment to a single cluster. Therefore, Node Affinity is correctly identified as the mechanism that enforces pod scheduling within a specific Kubernetes cluster.