What protocol is specifically used for clustered environments?

The protocol that is specifically used for clustered environments is Cluster Control Protocol (CCP). CCP is a proprietary Check Point protocol that is used for communication between cluster members and for cluster administration. CCP enables cluster members to exchange state information, synchronize connections, monitor interfaces, and perform failover operations. The other options are incorrect. Clustered Protocol, Synchronized Cluster Protocol, and Control Cluster Protocol are not valid terms in Check Point terminology. References: [Cluster Control Protocol (CCP) - Check Point Software]