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 Zones

  Why this is correct

  Availability Zones are physically separate locations within an Azure region, each with its own independent power, cooling, and networking infrastructure. By deploying application VMs across multiple zones, you ensure that if one datacenter (or an entire zone) fails, traffic can be served from the remaining healthy zones. This directly protects against a datacenter-level failure within the same region. VMs deployed across two or more zones qualify for the 99.99% uptime SLA, making this the correct choice for the stated requirement.

• ✗

  Availability Set

  Why it's wrong here

  An Availability Set provides high availability for VMs by distributing them across multiple fault domains (different racks with independent power and network) and update domains within a *single* Azure datacenter. It protects against local hardware failures, such as a server or rack going down, but it cannot protect against the failure of an entire datacenter because all VMs in an Availability Set share the same physical location. If that one datacenter experiences a catastrophic failure, all VMs in the set become unavailable. Availability Sets are therefore insufficient for the scenario described in the question.

  When this WOULD be correct

  A company wants to ensure high availability for their VMs within a single data center by distributing them across different physical racks and ensuring that during planned maintenance, not all VMs are updated simultaneously. In this scenario, an Availability Set would be the correct feature.

• ✗

  Azure Site Recovery

  Why it's wrong here

  Azure Site Recovery is designed for cross-region disaster recovery, not for protecting against a failure within a single Azure region. It continuously replicates your workloads to a paired secondary region and orchestrates failover to that separate region when a regional outage occurs. In the scenario of a single datacenter failure inside the primary region, Site Recovery would not automatically redirect traffic to another datacenter in the same region because it operates at the regional-pair level, not the zone level. While it is a powerful DR tool, it does not meet the requirement for intra-region, datacenter-level fault tolerance.

  When this WOULD be correct

  Azure Site Recovery would be correct if the question asked: 'Which service should be used to replicate VMs from one Azure region to another for disaster recovery in case of a regional outage?'

• ✗

  Azure Load Balancer

  Why it's wrong here

  Azure Load Balancer is a Layer-4 network service that distributes incoming traffic across healthy VMs in a backend pool using health probes. It can detect and remove an unhealthy VM, but it does not provide any physical redundancy or fault isolation for the underlying infrastructure. If all backend VMs are deployed in a single datacenter, a failure of that datacenter will take down every VM the load balancer is routing to, regardless of how intelligently it distributes traffic. Load balancing alone cannot protect against a datacenter failure; it must be combined with Availability Zones to achieve that level of resilience.

  When this WOULD be correct

  A question asking how to distribute incoming traffic evenly across multiple VMs in the same region to improve application responsiveness and fault tolerance at the network level, without requiring zone-level isolation.

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?”

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