Amazon RDS uses the replication functionality integrated into the MariaDB, MySQL, Oracle, PostgreSQL, and Microsoft SQL Server database engines to create a special type of DB instance called a Read Replica from a source DB instance.
A Read Replica may be in a different AWS Region than the primary DB instance region. In these cases, Amazon RDS sets up a secure communication channel between the primary DB instance and the Read Replica. Amazon RDS establishes the AWS security settings required to enable the secure channel, such as adding security group entries.
You can only replicate across AWS Regions when using the following Amazon RDS DB Instances: