AZ-305 Question 131
Single answerYou are designing a mission-critical e-commerce application hosted on Azure Virtual Machines for the front-end and Azure SQL Database for the back-end. The business requires 99.99% availability even in the event of a data center or zone outage. Currently, your front-end virtual machine scale set is deployed to a single Availability Zone in one region, and your SQL Database is configured with a single primary replica. Which design choice should you implement to meet the high availability requirement?
- A
Deploy an additional VM scale set in a second Availability Zone and configure Azure SQL Database Active Geo-Replication across regions
- B
Enable Zone Redundant Storage on the existing VM scale set disks and rely on Point-in-Time Restore for Azure SQL Database
- C
Use a single Availability Zone for VM scale sets and set up Azure SQL Database read replicas in the same zone
- D
Increase VM size to handle more load in the same Availability Zone and create a manual backup schedule for the Azure SQL Database
Show answer and explanation
Correct answer: A
Explanation
To achieve high availability in Azure, it is recommended to distribute compute resources across multiple zones (or regions, depending on your business continuity requirements) while ensuring your data tier also has a high-availability configuration. For Azure SQL Database, Active Geo-Replication provides multiple replicas in different regions for both high availability and disaster recovery. Refer to Microsoft’s documentation on high availability for virtual machines (https://learn.microsoft.com/azure/virtual-machines/availability) and Azure SQL Database (https://learn.microsoft.com/azure/azure-sql/database/high-availability-sla) for further best practices.
- A. Correct.
Option 1 is correct because deploying the front-end in multiple Availability Zones ensures resiliency within the region, and configuring Azure SQL Database Active Geo-Replication provides a secondary replica in another region. In case of a zone or regional outage, you can fail over to the secondary replica and maintain high availability.
- B. Incorrect.
Option 2 is incorrect because Zone Redundant Storage alone does not replicate the VM availability at the compute level across zones, and Point-in-Time Restore for Azure SQL Database is primarily a backup and restore feature, not an instant failover solution.
- C. Incorrect.
Option 3 is incorrect because a single Availability Zone for VM scale sets does not mitigate zone-level failures, and read replicas in the same zone do not protect against a zone-wide outage. Additionally, read replicas in Azure SQL Database are primarily for read-scale scenarios, not high availability failover.
- D. Incorrect.
Option 4 is incorrect because simply increasing the VM size does not address availability across different zones or regions. A manual backup schedule helps with data protection but does not provide the immediate failover required for high availability.