Final answer:
Servers in a cluster use a private cluster connection for communication, which ensures secure and high-performing interactions between the servers in the cluster.
Step-by-step explanation:
The servers connected in a cluster communicate with each other primarily through a private cluster connection. This type of connection is designed specifically for cluster communication and provides a dedicated network that is not shared with the public, ensuring both security and high-performance communication between the servers. Clusters may also use mechanisms like shared disk connections for accessing common storage, but for server-to-server communication within the cluster, a private network is the standard approach.