FIDO: 'not found' alarms from the fido_snmp test
When interacting with a device via SNMP, the snmp client receives OID and instance information. An OID can be thought of as an entry point into information of a certain class. For example, .22.214.171.124.126.96.36.199 is the OID for the ifTable, which contains information about interfaces. An instance is an arbitrary number that is mapped to humanly readable data such as interface name.
These bindings are not necessarily persistent. When the configuration is changed [software or hardware], or if a device reboots, these bindings can change. The behavior is dependent from device to device. Until caching applications 'relearn' these bindings by repolling, there can be a disconnect between device reality and an application's SNMP instance cache.
Many applications that interact with devices via SNMP cache SNMP instance information to improve performance, including FIDO. FIDO will let you know this because it will paint the row a yellow/green color and list the state as 'not found' instead of 'down'.
To help quickly clear out less useful alarms, the fido_snmp daemon will schedule a repoll of a device if it notices that the sysUptime counter has reset.