With SNMP adapter, metrics are created using MIB as the base object. Metrics are created only for the OIDs that Management Pack supports. These metrics are then monitored for all the devices that are attached with MIB file while configuring the adapter instance.
While creating a symptom, the SNMP adapter does not allow you to choose a specific device, you can only choose a specific component at a specific index from the existing inventory. For example, if you have to monitor all three Cisco fan modules for 'shutdown' status, you can create three symptoms for each fan module at each index(1,2 and 3), but you cannot choose a specific device. The symptoms will be generated for all devices that has fan modules at index (1,2 and 3).
If there are three Cisco switches (10.107.119.1, 10.107.119.2 and 10.107.119.3) in the environment, then each device has three fan modules at index 1, 2 and 3. When you create an alert using the symptoms, these alerts will be generated for all three Cisco switches. The following scenario explains how to selectively monitor a specific device using vRealize Operations Manager 'Custom Groups' and 'Policies'.