A Kubernetes controller automatically adds another pod replica to the resource pool in response to...

Horizontal Scaling (Scale Out):This involves addingmore instances(replicas/nodes) of a resource to handle increased load1111. In a Kubernetes or Runtime Fabric context, when the controller adds another "pod replica," it is strictly defined as horizontal scaling.

Vertical Scaling (Scale Up):This would involve increasing thesize(CPU or RAM capacity) of an existing single instance/pod2, rather than adding more copies of it.

Context:MuleSoft's Runtime Fabric (RTF) runs on Kubernetes and leverages this horizontal auto-scaling capability to maintain performance under high traffic.