This condition evaluates true for any non-system database other than distribution and ReportServerTempdb whose last differentiall backup is more than 48 hours old.
Restricted to SQL Server 2012 and higher
Ignores all system databases, distribution, and ReportServerTempDB databases.
Ignores Read Only databases
Ignores databases in a standby state
Ignores databases identified as a database snapshot
Default threshold is 48 hours, please change to meet your own SLA's
Set to check every 8 hours.