Which protocol is commonly used in network monitoring and operates over port 161?

The Simple Network Management Protocol, commonly known as SNMP, is the correct answer as it is specifically designed for network monitoring and management. It operates over port 161, allowing network devices like routers, switches, servers, and other hardware to be monitored and managed effectively. SNMP facilitates the collection of information from these devices and can also send commands to them to configure settings or retrieve status data.

This protocol plays a crucial role in managing network performance, tracking network health, and ensuring that devices are functioning correctly. Network administrators use SNMP to send queries to devices and receive responses that contain valuable operational data, which helps in monitoring traffic, diagnosing network issues, and planning for future capacity needs.

In contrast, protocols like Secure Socket Layer (SSL), Hypertext Transfer Protocol (HTTP), and File Transfer Protocol (FTP) serve very different purposes related to securing communications, transferring web data, and transferring files, respectively. They do not provide the same functionalities that SNMP does for network management, making SNMP the appropriate choice for this question.