AZ-305 Multi-master writes Practice Question
You are designing a business continuity solution for a critical application that uses Azure Cosmos DB with multiple write regions. The application is deployed in the East US and West Europe regions. The business requires that if one region fails, the application can continue to serve writes in the remaining region with no data loss. Which consistency level should you use?
⚠ Common exam trap
Candidates often assume that strong consistency is available with multiple write regions, but it is not. They may also think that Bounded staleness guarantees zero data loss, but it only provides a bounded lag, not complete data loss prevention.
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
✓
Bounded staleness
Azure Cosmos DB does not support strong consistency when multiple write regions are enabled. The supported consistency levels for multi-region writes are Eventual, Session, and Bounded staleness. None of these guarantees zero data loss during a regional failure, because writes that have not yet been replicated to the surviving region can be lost. Bounded staleness limits how far the data can lag behind, but it does not eliminate data loss. To meet a strict no-data-loss requirement, you must use a single write region with strong consistency (or another architecture that ensures synchronous replication before acknowledging writes). Therefore, the requirement as stated cannot be satisfied by any of the listed consistency levels in a multi-write-region configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Strong
Why it's wrong here
Strong consistency is not supported when multiple write regions are enabled. This option is incorrect because it cannot be used in this scenario.
- ✗
Eventual
Why it's wrong here
Eventual consistency provides no ordering or recency guarantees and is the weakest level. It does not minimize data loss and is not the best choice for critical applications.
- ✗
Session
Why it's wrong here
Session consistency guarantees monotonic reads and writes within a client session but does not provide region-level consistency. It is not designed to prevent data loss across regions.
- ✓
Bounded staleness
Why this is correct
Bounded staleness is the strongest consistency level supported with multi-master writes. It provides a bounded lag on data staleness, which helps minimize data loss compared to Eventual or Session, though it cannot guarantee zero data loss.
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Related to this question
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Multi-Region Active-Active Architecture
Key term
Cosmos DB Design
Cosmos DB Design is the process of structuring data and choosing configuration settings in Azure Cosmos DB to ensure fast performance, low cost, and scalability for applications.
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.
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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.