The agent IP address is sent as “0.0.0.0″ when you use the SnmpSendMsg function to send an SNMPv1 trap to an external SNMP manager
When you run an application that sends a Simple Network Management Protocol version 1 (SNMPv1) trap to an external SNMP manager by using the SnmpSendMsg function directly, the agent IP address is sent as “0.0.0.0″. If you use Microsoft Network Monitor to capture the packet, the AgentAddress in the Protocol Data Units (PDU) appears as “NULL”.
Note: This problem occurs on a Windows Server 2008-based computer or on a Windows Vista-based computer.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB967181.