You are using a single Cloud SQL instance to serve your application from a specific zone. You want to introduce high availability. What should you do?

Creating a failover replica instance in the same region but a different zone is the correct approach to introduce high availability for a single Cloud SQL instance. This configuration ensures that if the primary instance or its zone becomes unavailable, Cloud SQL can automatically fail over to the replica, minimizing downtime. Read replicas are for scaling read operations and do not provide automatic failover for the primary instance. Placing the failover replica in a different region would introduce higher latency for replication and failover, and is typically used for disaster recovery rather than high availability within a single region.