aws rds describe-source-regions
Returns a list of the source Amazon Web Services Regions where the current Amazon Web Services Region can create a read replica, copy a DB snapshot from, or replicate automated backups from. AWS CLI reference
4 options Its page in the AWS CLI reference
Options
--filtersThis parameter isn't currently supported.--markerAn optional pagination token provided by a previous DescribeSourceRegions request.--max-recordsThe maximum number of records to include in the response.--region-nameThe source Amazon Web Services Region name.