Basic Concept: This question tests high availability and disaster recovery design for Azure SQL, SQL Server on Azure VMs, and regional failure scenarios.
Why C is Correct: differential is part of the availability or recovery design space, but the correct choice must satisfy the specified failover, restore, quorum, RPO, or RTO requirement. The scenario asks for: You need to recommend a backup solution to restore DB3. That makes differential the option that satisfies the required Azure SQL layer and operational outcome.
Why A is Wrong: transaction log is part of the availability or recovery design space, but the correct choice must satisfy the specified failover, restore, quorum, RPO, or RTO requirement. It handles a different resilience pattern and would not deliver the failover or recovery behavior required here.
Why B is Wrong: point-in-time restore (PITR) is part of the availability or recovery design space, but the correct choice must satisfy the specified failover, restore, quorum, RPO, or RTO requirement. It is not wrong technology in general, but it is the wrong HA/DR control for this scenario ' s failure model.
Why D is Wrong: long-term retention (LTR) is part of the availability or recovery design space, but the correct choice must satisfy the specified failover, restore, quorum, RPO, or RTO requirement. It handles a different resilience pattern and would not deliver the failover or recovery behavior required here.
