Explanation: Amazon Relational Database Service (Amazon RDS) is a managed service that makes it easy to set up,operate, and scale a relational database in the cloud. It provides cost-efficient and resizable capacity,while managing time-consuming database administration tasks, freeing you up to focus on yourapplications and business. When you create or modify your DB Instance to run as a Multi-AZ deployment, Amazon RDSautomatically provisions and maintains a synchronous "standby" replica in a different AvailabilityZone. Updates to your DB Instance are synchronously replicated across Availability Zones to thestandby in order to keep both in sync and protect your latest database updates against DB Instancefailure. During certain types of planned maintenance, or in the unlikely event of DB Instance failureor Availability Zone failure, Amazon RDS will automatically failover to the standby so that you canresume database writes and reads as soon as the standby is promoted. Since the name record foryour DB Instance remains the same, your application can resume database operation without theneed for manual administrative intervention. With Multi-AZ deployments, replication is transparent:you do not interact directly with the standby, and it cannot be used to serve read traffic. If you areusing Amazon RDS for MySQL and are looking to scale read traffic beyond the capacity constraints ofa single DB Instance, you can deploy one or more Read Replicas. Reference: http://aws.amazon.com/rds/faqs/