AZ-305 Design data storage solutions Practice Question
Contoso, Ltd. is migrating a legacy on-premises application to Azure. The application uses a SQL Server database with complex queries and requires read-heavy workloads with sub-10-millisecond latency. The solution must support geo-replication for disaster recovery. Which Azure data service should you recommend?
⚠ Common exam trap
A common mix-up: candidates choose Hyperscale for its scalability and geo-replication features, overlooking that its page server architecture introduces higher read latency for small, frequent queries compared to the local SSD-based Business Critical tier.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure SQL Database Business Critical
Azure SQL Database Business Critical is correct because it uses SQL Server database engine with full T-SQL support for complex queries, provides read-heavy workloads with sub-10-millisecond latency via in-memory OLTP and local SSD storage, and supports active geo-replication for disaster recovery. This tier offers a readable secondary replica in a different Azure region, meeting both latency and geo-replication requirements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Azure Cosmos DB for NoSQL
Why it's wrong here
Azure Cosmos DB for NoSQL is a globally distributed, multi-model database with a schema-agnostic, horizontally partitioned architecture, not a relational engine despite its SQL-like query dialect. It lacks the full T-SQL capabilities—multi-table joins, window functions, and complex procedural logic—that a legacy on-premises application likely relies on, so the application would require substantial rewriting and data model redesign rather than a straightforward migration.
- ✓
Azure SQL Database Business Critical
Why this is correct
Azure SQL Database Business Critical uses a premium storage and compute architecture based on Always On Availability Groups, providing multiple readable secondary replicas that can serve read-only traffic for low-latency read-heavy workloads. It also supports active geo-replication across Azure regions, giving disaster recovery and regional read access without changing the application's T-SQL code, and its fully compatible relational engine makes it the best fit for a legacy application that needs both read scaling and minimal migration risk.
- ✗
Azure SQL Database Hyperscale
Why it's wrong here
Hyperscale is built as a distributed storage architecture that uses page servers and a log-based compute node, allowing a massive database footprint (up to 100 TB) and rapid scale-up, but this architecture is not inherently tuned for low-latency read-heavy queries. Although Hyperscale provides read replicas, its primary design goal is elastic scalability for very large database workloads, not the predictable, in-memory, low-latency read path that Business Critical's Always On secondaries deliver.
- ✗
Azure SQL Managed Instance Business Critical
Why it's wrong here
Azure SQL Managed Instance Business Critical is a SQL Server engine in a virtual network with nearly total surface-area compatibility, ideal for lift-and-shift, but its geo-replication story is limited to failover groups between managed instances rather than the fine-grained active geo-replication available in Azure SQL Database. Because traffic to a managed instance traverses a virtual network and a dedicated subnet, connection latency can be higher than Azure SQL Database's PaaS regional endpoint, making it less attractive for a low-latency, read-heavy application that needs global reach.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-305 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-305 exam.