Microsoft Azure Solutions Architect Expert AZ-305 Practice Question

Azure SQL Managed Instance in the Business Critical tier is a fully managed PaaS offering that provides near-100% compatibility with on-premises SQL Server, so application code and database features rarely need modification after migration. Because it is a managed service, Microsoft handles OS and database patching and supplies automated backups with up to 35-day retention by default. The Business Critical tier uses a four-node Always On availability group architecture that can be configured as zone-redundant, giving synchronous replication across multiple availability zones within a region and ensuring high availability without additional administration. It also places the primary and replicas on local SSD storage, supporting single-digit-millisecond latency for both reads and writes.

In contrast, a single Azure SQL Database in the Premium tier might require feature changes due to lower compatibility and does not guarantee instance-level features. An Azure SQL Virtual Machine would still leave patching and backup management to the customer and would require manual configuration of an availability group. The Hyperscale service tier offers high scalability but provides asynchronous replicas only and is not designed primarily for synchronous zone-redundant HA. Therefore, the Managed Instance Business Critical tier best meets all stated requirements.