AZ-305 Design business continuity solutions Practice Question
A company runs a critical line-of-business application on Azure VMs within a single region. The application tier is deployed across multiple VMs. They need to protect against a failure of an entire Azure datacenter within that region. The solution should automatically distribute the VMs across physically separate locations with independent power, cooling, and networking. The company also requires the lowest possible latency between application and database tiers within the same location. Which deployment strategy should they use?
⚠ Common exam trap
Candidates often confuse availability sets (which protect against rack failures) with availability zones (which protect against datacenter failures), or they incorrectly assume that cross-region replication via Site Recovery is the only way to achieve datacenter fault tolerance, ignoring the lower-latency option of multiple zones within the same region.
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
✓
Deploy the VMs across multiple availability zones
Availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Deploying the application tier VMs across multiple zones protects against an entire datacenter failure while keeping all resources within the same region, ensuring the lowest possible latency between application and database tiers when they are placed in the same zone.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Deploy the VMs across multiple availability zones
Why this is correct
Availability zones provide datacenter-level redundancy within a region. By placing VMs in different zones, the application can survive a single datacenter failure. This also allows low latency within the same zone for the database tier.
- ✗
Deploy the VMs in an availability set
Why it's wrong here
An availability set distributes virtual machines across fault domains and update domains within a single Azure datacenter, which only shields against localized hardware failures such as a failed node, rack, or network switch. It does not span multiple datacenter buildings, so if that entire datacenter goes offline, all VMs in the set become unavailable together. Because the requirement is to survive a full datacenter outage, an availability set falls short and fails to provide the zone-level isolation that availability zones deliver.
- ✗
Use Azure Site Recovery to replicate VMs to a paired region
Why it's wrong here
Azure Site Recovery is a disaster recovery service that asynchronously replicates VMs to a secondary paired region, not to a different availability zone in the same region. While it can restore workloads after an entire regional disaster, it introduces cross-region replication delays, potential data loss (with default asynchronous replication), and manual failover steps that extend recovery time. The stated need is for protection against a datacenter failure within the current region, not a regional outage, so Site Recovery over-engineers the solution while failing to provide the low-latency, same-region redundancy the application requires.
- ✗
Use Azure Proximity Placement Groups
Why it's wrong here
A proximity placement group is designed to co-locate VMs physically close together within the same datacenter or even on the same rack, minimizing network latency between tiers. This grouping deliberately increases the blast radius of a single failure point, since all VMs in the group are susceptible to the same datacenter-level outage. It offers no redundant distribution across zones or fault domains, so using it would actively make the application less resilient to a datacenter failure rather than more resilient.
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JA
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.