Question 846 of 981
AZ-900 Describe cloud concepts Practice Question
What is the primary advantage of deploying VMs across multiple Azure Availability Zones instead of a single Availability Set?
⚠ Common exam trap
Test-takers frequently confuse Availability Zones with Availability Sets, thinking both provide the same level of resilience, but the key difference is that Zones protect against datacenter-level failures while Sets only protect against rack-level failures within a single datacenter.
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
✓
Protection against datacenter-level failures with a higher SLA (99.99% vs. 99.95%)
Azure Availability Zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Deploying VMs across multiple zones protects against a complete datacenter failure, enabling a 99.99% VM-to-VM connectivity SLA. In contrast, an Availability Set protects against hardware failures within a single datacenter (e.g., rack or update domain failures) and offers a 99.95% SLA.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
VMs in different Availability Zones are always cheaper than Availability Sets
Why it's wrong here
There is no cost discount for deploying VMs across Availability Zones; compute pricing per VM is identical whether you use an Availability Set or an Availability Zone. The difference lies in fault isolation, not in the per-VM rate. In fact, cross-zone network traffic can incur data transfer egress charges, so a zonal deployment might be more expensive, not cheaper.
- ✓
Protection against datacenter-level failures with a higher SLA (99.99% vs. 99.95%)
Why this is correct
Availability Zones are physically distinct datacenters within an Azure region, each with independent power, cooling, and networking. If one zone experiences a datacenter-level failure, VMs in other zones remain available, providing protection that an Availability Set cannot offer. Azure backs this with a 99.99% SLA for multi-VM deployments across zones, compared to 99.95% for VMs in an Availability Set, which is a significant availability advantage.
- ✗
VMs automatically scale in response to demand when placed in Availability Zones
Why it's wrong here
Availability Zones define where a VM is physically hosted; they do not include any automatic scaling behavior. To scale VMs in response to demand, you must use Azure Virtual Machine Scale Sets with autoscale rules, optionally paired with a load balancer. Deploying individual VMs across zones simply makes them fault-tolerant—it does not make them self-scaling. Therefore, this statement mistakenly conflates architectural redundancy with autoscaling.
- ✗
Availability Zones reduce network latency between VM instances
Why it's wrong here
Placing VMs in different Availability Zones increases resilience but not network speed. Traffic between zones must travel across datacenter boundaries, which can add a slight latency increase compared to communication between VMs in the same zone or within an Availability Set. Availability Zones are a high-availability solution, not a low-latency one; they do not reduce network latency between VM instances.
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Last reviewed: Jun 11, 2026
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