Final answer:
In SNMP communication, the agent sends a GetResponse to the manager after receiving either a GetRequest or GetNextRequest.
Step-by-step explanation:
When an SNMP manager sends a GetRequest or GetNextRequest to an agent, the response from the agent is a GetResponse. This core function of SNMP is essential for the manager to retrieve the value of specific variables or a list of variables from the agent. If the manager sends a SetRequest, it intends to modify the value of an SNMP agent's variable. The Trap is an unsolicited message from the agent to the manager, indicating that a certain event has occurred. Lastly, the GetBulkRequest is used to efficiently retrieve voluminous data from a large MIB (Management Information Base) subtree.