Which of the following server roles utilize a heartbeat/polling process? (Choose two.)

A proxy server acts as an intermediary; while it might monitor upstream servers, 'heartbeat/polling process' is not a defining characteristic of its primary role like it is for clusters or load balancers.

A certificate authority issues and manages digital certificates; its primary function does not typically involve heartbeat/polling processes for its core service.

A logging server collects and stores logs; its main function is data aggregation, not active health monitoring via heartbeat.

A file server stores and provides access to files; while it needs to be up, its core role doesn't inherently involve a heartbeat/polling mechanism in the same way as cluster nodes or load-balanced services.

Cluster servers use heartbeat mechanisms to monitor the health and availability of other nodes within the cluster. If a node fails to send a heartbeat, it's considered offline, and resources can be failed over to a healthy node, ensuring high availability.

Load balancers utilize polling (health checks) to determine the availability and responsiveness of backend servers. They continuously check if servers are alive and capable of handling requests before forwarding traffic to them.