AZ-305 Question 135
Single answerYou are designing a mission-critical order processing system that runs on Azure Virtual Machines. The system should fail over automatically if the primary region goes offline. The organization also wants to keep operating costs low while meeting high availability requirements. Which deployment strategy best meets these needs?
- A
Deploy two VMs in a single Availability Set within the primary region only
- B
Deploy multiple VMs in multiple Availability Zones in the same region and configure a Load Balancer
- C
Deploy a VM Scale Set across two Availability Zones in the same region and use Azure Traffic Manager
- D
Deploy identical sets of VMs in two different Azure regions, fronted by Azure Traffic Manager configured for failover
Show answer and explanation
Correct answer: D
Explanation
High availability for compute resources in Azure requires protecting against both local hardware failures (through Availability Sets or Zones) and region-wide outages. According to Microsoft’s best practices (docs.microsoft.com/azure/architecture/best-practices/availability), deploying resources across multiple regions is essential for true disaster recovery. Using Azure Traffic Manager (or Azure Front Door with failover routing) allows automatic redirection of traffic if the primary region becomes unavailable, ensuring minimal downtime with a cost-effective active-passive setup.
- A. Incorrect.
Option 1 is incorrect because using just a single Availability Set in one region does not cover region-wide failures. While it protects against hardware failures within the data center, it doesn’t provide automatic failover to another region.
- B. Incorrect.
Option 2 is incorrect because Availability Zones in one region protect only against local datacenter failures. If the entire region experiences a catastrophic outage, you still have no failover in another region.
- C. Incorrect.
Option 3 is incorrect because while a VM Scale Set with Azure Traffic Manager can distribute traffic across zones, this still spans only a single region unless you explicitly replicate into multiple regions. By itself, this option does not provide cross-region high availability.
- D. Correct.
Option 4 is correct. Deploying identical VM instances in two geographically separate regions and using Azure Traffic Manager in failover mode provides regional redundancy. If the primary region fails, traffic is automatically routed to the secondary region, reducing downtime. This approach meets high availability requirements and keeps costs manageable by only actively running a second set of VMs in another region.