AZ-305 Design business continuity solutions Practice Question
A company runs a critical application on Azure VMs in a single region. The application writes data to Azure SQL Database (PaaS) and Azure Blob Storage. The company needs a disaster recovery plan with an RPO of less than 5 minutes for the database and less than 15 minutes for the blob storage, and an RTO of less than 1 hour for the entire solution. What should they recommend?
⚠ Common exam trap
A common mix-up: candidates confuse geo-redundant storage (GRS) with read-access geo-redundant storage (RA-GRS), not realizing that GRS requires a storage account failover to access the secondary region, which can take up to an hour and thus fails the RTO requirement.
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
✓
Use Azure Site Recovery for VMs, active geo-replication for Azure SQL Database, and read-access geo-redundant storage (RA-GRS) for Blob Storage.
Azure Site Recovery provides the VM replication needed to meet the RTO of under 1 hour, active geo-replication for Azure SQL Database offers a configurable RPO of as low as 5 seconds (well under the 5-minute requirement), and RA-GRS for Blob Storage provides read-access to a secondary region with an RPO typically under 15 minutes, enabling fast failover and read access during a disaster.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Azure Site Recovery for VMs, geo-replication for Azure SQL Database, and geo-redundant storage (GRS) for Blob Storage.
Why it's wrong here
GRS provides geo-redundant storage but does not offer read access in the secondary region without failover, which could delay recovery. Also, geo-replication for SQL DB is not the standard name; active geo-replication is needed for low RPO.
- ✗
Use Azure Backup for VMs, geo-redundant storage for SQL Database backups, and geo-redundant storage for Blob Storage.
Why it's wrong here
While Azure Backup ensures crash-consistent or file-consistent snapshots, it is fundamentally a backup service, not a disaster-recovery replication engine: VM restore RTO typically ranges from hours to a day because entire machines must be retrieved from vault storage, and the RPO is bounded by the scheduled backup frequency (often 12–24 hours), not by continuous replication. The same limitation applies to geo-redundant storage for SQL Database backups, which protects backup files but does not maintain a live, readable secondary database; failover would require restoring from the latest backup, incurring data loss and unacceptable recovery time. Additionally, GRS for Blob Storage without read access forces a wait for a full failover before you can access the secondary copy, so it fails the sub-1-hour RTO and minimal RPO requirements. Thus, this option is a backup-centric plan, not a rapid DR solution.
- ✓
Use Azure Site Recovery for VMs, active geo-replication for Azure SQL Database, and read-access geo-redundant storage (RA-GRS) for Blob Storage.
Why this is correct
ASR replicates VMs with minutes RPO. Active geo-replication for Azure SQL Database provides a readable secondary with RPO seconds. RA-GRS provides a readable copy in the secondary region with ~15 minute RPO, meeting the blob requirement.
- ✗
Use Azure Front Door with multi-region deployment of VMs and Azure Cosmos DB for the database.
Why it's wrong here
Azure Front Door is a global layer-7 load balancer that can route traffic to multi-region deployments, but it does not itself replicate or protect the underlying VMs—those VMs would still need a DR mechanism like Site Recovery or an active-active design with replicated compute and storage. More critically, swapping the required Azure SQL Database for Azure Cosmos DB fundamentally changes the application's data platform: Cosmos DB is a NoSQL document database, so existing relational schemas, T-SQL queries, transactions, and stored procedures would require a substantial rewrite and data migration, making it a costly redesign rather than a drop-in DR solution. Furthermore, this option makes no provision for geo-replicated Blob Storage, leaving that component entirely unaddressed. Therefore, even with Front Door and a multi-region footprint, this approach pivots the architecture rather than meeting the existing DR requirements.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
Go deeper
Related to this question
Learn chapter
Designing Azure Storage Solutions
Key term
Azure Site Recovery
Azure Site Recovery is a Microsoft Azure service that keeps your business applications and data running by automatically replicating them to a secondary location and failing over if the primary site goes down.
Key term
Disaster Recovery Design
Disaster Recovery Design is the process of planning and implementing strategies to restore IT systems and data after a catastrophic failure, ensuring business continuity with minimal downtime and data loss.
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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.