AZ-305 Practice Question 17: Web Tier Zone Availability
Microsoft Azure Solutions Architect Expert (AZ-305) · Test 2 · question 7 of 10
A university is deploying a two-instance web tier on Azure virtual machines in a region that supports availability zones. The service must stay available if a single Azure datacenter in the region is lost, for example through a power or cooling failure that affects one physical facility, and traffic must keep reaching whichever instance survives. Multi-region deployment is out of scope for this phase.
What should you recommend?
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Answer:
An availability zone is a physically separate zone within an Azure region with its own power, network, and cooling, and Microsoft describes spreading replicated virtual machines across zones as the way to protect apps and data from the loss of a datacenter. Placing the two instances in two zones and fronting them with a zone-redundant Standard Load Balancer means neither the compute nor the entry point depends on one facility.
Option A protects against a smaller failure. An availability set distributes virtual machines across fault and update domains (separate racks and separate maintenance batches) *inside one datacenter*, which carries the 99.95% virtual machine SLA but offers nothing when the whole facility is lost.
Option B changes the storage, not the failure domain. Both instances still sit in one zone, so a zone loss takes the service down; the disk type affects performance and single-instance availability, not resilience to a datacenter outage.
Option C confuses a management boundary with a failure boundary. Resource groups are metadata containers and have no bearing on physical placement; both machines could land in the same datacenter. Traffic Manager is a DNS-based global load balancer intended for endpoints in different regions, and it adds DNS TTL delays without solving the zone problem.