Simple Network Management Protocol, known as SNMP for short, is used to log and manage network devices and applications. SNMP can be used to configure devices and applications remotely, but if left unsecured, it can also be used to pull down information about said application and devices. This information can be used to get a better understanding of the network:
snmpwalk 192.16.1.1 -c PUBLIC
-c: This is a community string to authenticate to a device.