Which firewall port needs to be opened between your HPE Aruba Networking CX switches and...

The correct answer is D. UDP 162. SNMP monitoring commonly uses two different UDP ports depending on direction and purpose. SNMP polling requests and responses use UDP 161, while SNMP traps and notifications are sent to a monitoring or management station on UDP 162. The question specifically asks about sending monitoring alerts using SNMP, which refers to SNMP traps or notifications from the switch to the Network Monitoring System. HPE Aruba Networking AOS-CX SNMP documentation states that the snmp-server host command configures a trap or inform receiver to which the SNMP agent sends SNMP traps or informs. The same documentation identifies the UDP port parameter for notifications and lists the default as 162. Therefore, the required firewall allowance for SNMP alert notifications from CX switches to the NMS is UDP 162. Option A is incorrect because TCP 161 is not the standard SNMP polling transport. Option B and option C use incorrect ports and protocols for SNMP alert delivery.