AZ-900 Describe cloud concepts 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.

• ✗

  Two datacenters within the same city connected by high-speed fiber

  Why it's wrong here

  Describing two datacenters within the same city connected by high-speed fiber is exactly how availability zones are built—multiple physically separate facilities in the same metropolitan area with independent power, cooling, and networking, linked by low-latency fiber. That architecture protects against individual datacenter or rack failures, but it cannot protect against a citywide disaster, which is why it does not meet the definition of a region pair. Region pairs require a much larger geographic separation (300+ miles) to isolate customers from regional-scale events and to support Azure's disaster recovery guarantees.

• ✓

  Two Azure regions paired for disaster recovery and update isolation

  Why this is correct

  Azure region pairs are two regions within the same geography that are at least 300 miles apart and are directly coupled by Azure for two critical purposes: disaster recovery and coordinated platform updates. When a region fails, the paired region is prioritized for recovery, and during planned maintenance, Azure sequences updates so that only one region in the pair is updated at a time, reducing the risk of simultaneous downtime. This ensures that customers using paired regions for geo-redundancy (e.g., with GRS) have a designed recovery path that is physically and logically isolated from the primary region.

• ✗

  Two subscriptions in the same Azure AD tenant

  Why it's wrong here

  Subscriptions and Azure AD tenants are logical constructs for managing access, billing, and identity; they do not correspond to any physical datacenter location. Two subscriptions in the same Azure AD tenant can have resources deployed in any regions, and those regions may or may not be paired. Region pairs are a physical infrastructure relationship between two specific Azure regions within a geography, used for disaster recovery and update sequencing—they have no dependency on how subscriptions or tenants are organized.

• ✗

  Primary and secondary zones within a single Azure region

  Why it's wrong here

  Availability zones are physically separate datacenters within a single Azure region, providing high availability by distributing workloads across fault domains. They are not 'primary' and 'secondary' zones, and they do not span hundreds of miles. Region pairs, by contrast, are two distinct Azure regions paired at the platform level specifically for disaster recovery and to ensure that platform updates are not applied to both regions simultaneously, which availability zones cannot do because they share the same regional boundary and cannot survive a regional outage.

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