AZ-900 Describe Azure architecture and services Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Availability set

  Why it's wrong here

  An availability set distributes VMs across multiple fault domains (shared power and network) and update domains (maintenance scheduling) within a single Azure datacenter. While this protects against hardware failures or planned maintenance events inside that datacenter, it does not span separate physical datacenters. Therefore, an availability set cannot guard against an outage that takes down the entire datacenter, which is the specific requirement described in the scenario.

  When this WOULD be correct

  An availability set would be correct if the requirement was to protect against rack-level failures within a single Azure data center, such as ensuring VMs are placed on different racks with separate power and networking.

• ✓

  Availability zone

  Why this is correct

  Availability zones are physically distinct datacenters within an Azure region, each with independent power, cooling, and networking. By deploying VMs across multiple zones, you ensure that at least one instance remains operational if a single datacenter suffers a catastrophic failure. This configuration also qualifies for the 99.99% virtual machine SLA, which is exactly the level of isolation required to protect against an entire datacenter going offline.

• ✗

  Proximity placement group

  Why it's wrong here

  A proximity placement group is designed to colocate VMs as close as possible, often in the same datacenter or even within the same rack, to minimize network latency for tightly coupled workloads. This intentional concentration of resources reduces fault isolation rather than improving it, because a single datacenter failure would potentially affect all VMs in the group. Since the requirement demands separation across distinct datacenters, a proximity placement group is the opposite of the correct solution.

  When this WOULD be correct

  A company deploys a latency-sensitive application where VMs must be as close as possible to each other within the same data center to minimize network latency. They should use a proximity placement group to ensure VMs are co-located.

• ✗

  Azure Load Balancer

  Why it's wrong here

  Azure Load Balancer distributes incoming traffic but does not inherently ensure that VMs are placed in different physical locations. It can work with availability sets or zones, but it is not the construct for physical placement.

  When this WOULD be correct

  A question requiring high availability and load balancing for web tier VMs across multiple availability zones or within the same zone, such as 'A company needs to distribute incoming web traffic across multiple VMs to ensure no single VM is overwhelmed. Which Azure construct should they use?'

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”