The SDM uses the read-only community string of a device for SNMP discovery. If a read-only community string for a device is changed per the instructions in SNMP Community String Parameters, the string will automatically be appended to the list of candidate discovery strings. The SDM uses the list of candidate discovery strings whenever an SNMP discovery operation is initiated.
This offers great convenience, because it allows the SDM to discover other devices, whether they are using the default read community string, the latest read community string, or any other read community strings which were used in the past.
The operator can view the list of candidate discovery strings as shown below. The operator can manually edit the list as well, if desired.