
Explanation:
Box 1: Active Geo-Replication
Data must sync continuously between primary and secondary replicates.
Read-only secondary replicas must be supported.
For read-only secondary replicas with continuous sync between primary and secondary in Azure SQL Database, you should use Active Geo-Replication. This feature replicates data from a primary database to a readable secondary database, ensuring consistency between them. You can configure this even across different Azure regions for disaster recovery or to scale read workloads.
Box 2: Failover Groups
Data must sync continuously between primary and secondary replicates.
The connection string must remain unchanged after a failover
Multiple databases must be able to fail over simultaneously
To enable multiple Azure SQL databases to fail over simultaneously and sync continuously between primary and secondary replicates, you should use Failover Groups. This solution provides the necessary features for managing the replication and failover of a group of databases.
Reference:
https://learn.microsoft.com/en-us/azure/azure-sql/database/active-geo-replication-overview
https://learn.microsoft.com/en-us/azure/azure-sql/database/failover-group-sql-db