Which statement is true regarding SNMP traps from the given IP address?

The statement that traps are allowed from the specified IP address, 10.21.15.16, reflects a scenario where the network device has been configured to accept SNMP traps specifically from that address. This is a common security practice in network management, where devices are set up to only accept SNMP messages from trusted sources. By design, this selective acceptance helps to reduce the risk of unauthorized or malicious SNMP traps affecting the network management system, ensuring that only valid data is processed.

In many SNMP configurations, network administrators specify certain IP addresses that are permitted to send traps. This is often done to enhance the security posture of the network, as it limits incoming traffic to known sources, thereby minimizing the attack surface.

Other options imply broader or more lax compliance regarding SNMP traps, which is typically not aligned with best practices in network security. For example, rejecting traps from all unknown sources effectively would contribute to a secure environment, while allowing traps from any address introduces risks. Additionally, requiring special authentication for SNMP trap senders is not a standard practice with SNMP version 1 or 2c, focusing more on community string for basic security, whereas SNMPv3 does indeed implement such authentication as part of its security features.