once receiving node will get the request then it will acknowledge the request and will send the GossipDigestAckMessage.
ACK2 – Finally, the initial node will get acknowledge then it will send GossipDigestAck2Message to the receiving node to acknowledge the acknowledgment response from receiving node. Working steps of Gossip protocol :
Initially, To receive endpoint state information, it will be done when Cassandra DB starts up, it registers itself with the Gossiper. After that, Periodically, typically once per second then Gossiper will choose the random node in a ring to start a Gossip session. After that, Initiating node will send the request GossipDigestSynMessage to the receiving node which simply means that it is requesting a synchronization. After that, when receiving node will get the request then it will acknowledge the request with GossipDigestAckMessage message to acknowledge the request. Finally, when Initiating node will get the acknowledgment from receiving node then again it will send the acknowledgment with GossipDigestAck2Message.