RDS replicas do not provide out of the box load balancing capability amongst all running readers. Each once has its own endpoint, and you would have to manually put a load balancer/driver in front of it for re-routing connections as per requirement.
In Aurora the single cluster endpoint will always connect to the single read/write instance in the cluster. The replicas are read only and must be chosen explicitly by the application in order to be used. RDS replicas function the same way. In order to switch between them you need to run a load balancer for the DB or you need to have your application choose which database to use.
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