AZ-305 Question 129
Select 2You have a mission-critical e-commerce application running on a set of Azure VMs for the front-end and an Azure SQL Database for data storage. Currently, everything is hosted in a single Azure region, within a single Availability Zone. When that Availability Zone experiences an outage, the application becomes completely unavailable. You must redesign the solution so that it remains available if any single Availability Zone in the same region fails. Which two strategies should you implement to meet this goal?
- A
Deploy the VMs across multiple Availability Zones in the region and place them behind a zone-redundant Standard Load Balancer.
- B
Place the VMs in an Availability Set within the existing Availability Zone to improve resilience within that zone.
- C
Configure the Azure SQL Database tier to support zone redundancy, ensuring your database remains available if one zone goes down.
- D
Use ephemeral OS disks for the VMs to reduce storage dependency on the current Availability Zone.
Show answer and explanation
Correct answers: A, C
Explanation
To achieve high availability within a single region, you must ensure both the application tier and the data tier can withstand the loss of an entire Availability Zone. Placing VMs across multiple zones and using a zone-redundant load balancer addresses compute-layer redundancy. Configuring Azure SQL Database for zone redundancy (in suitable tiers) ensures the database remains available if one zone fails. For more information, see Microsoft’s official guidance on Availability Zones (https://learn.microsoft.com/azure/availability-zones/az-overview) and Azure SQL Database high availability (https://learn.microsoft.com/azure/azure-sql/database/high-availability-sla).
- A. Correct.
Correct. Distributing VMs across multiple zones with a Standard Load Balancer that supports zone redundancy helps maintain availability if a single zone fails. This design spreads instances to different zones, mitigating the impact of a single zone outage.
- B. Incorrect.
Incorrect. An Availability Set only helps distribute VMs across multiple fault domains and update domains within the same zone. It does not protect against zone-wide failures.
- C. Correct.
Correct. Azure SQL Database Business Critical and Premium tiers can be configured for zone redundancy, keeping the database available even if one zone goes down. This ensures the data layer remains accessible during a zone outage.
- D. Incorrect.
Incorrect. Ephemeral OS disks can improve performance and reduce data latency, but they do not protect against a full zone outage. If the zone hosting the VMs fails, ephemeral disks alone do not ensure availability in other zones.