How many levels or zones does Amazon RDS support for replication setup?

Amazon RDS supports replication setup at multiple levels:

• Intra-Availability Zone (AZ) Replication — to increase fault tolerance within a single zone.
• Inter-Zone Replication (Multi-AZ) — automatic data duplication across different availability zones to ensure high availability.
• Read Replicas — creating copies of the database in one or more zones or regions for read scaling and geographic distribution.

Thus, three main levels or zones of replication setup can be distinguished: within a single AZ, between AZs (Multi-AZ), and between regions (Read Replicas).