Which of the following port numbers the SNMP protocol uses?

(A) 20
(B) 25
(C) 160
(D) 161

161 is the correct answer.

Simple Network Management Protocol (SNMP) – Port 161. SNMP is an application layer protocol used specifically for network device management. For example, Cisco supplies a large variety of network management products, many of them in the Cisco Prime network management software product family. They can be used to query, compile, store, and display information about a network’s operation. To query the network devices, Cisco Prime software mainly uses SNMP protocols.