Regions and Availability Zones in Azure

Microsoft Azure services are available globally to drive your cloud operations at an optimal level. You can choose the best region for your needs based on technical and regulatory considerations: service capabilities, data residency, compliance requirements, and latency.

Terminology

To better understand regions and Availability Zones in Azure, it helps to understand key terms or concepts.

Term or concept Description
region A set of datacenters deployed within a latency-defined perimeter and connected through a dedicated regional low-latency network.
geography An area of the world containing at least one Azure region. Geographies define a discrete market that preserve data residency and compliance boundaries. Geographies allow customers with specific data-residency and compliance needs to keep their data and applications close. Geographies are fault-tolerant to withstand complete region failure through their connection to our dedicated high-capacity networking infrastructure.
Availability Zone Unique physical locations within a region. Each zone is made up of one or more datacenters equipped with independent power, cooling, and networking.
recommended region A region that provides the broadest range of service capabilities and is designed to support Availability Zones now, or in the future. These are designated in the Azure portal as Recommended.
alternate (other) region A region that extends Azure's footprint within a data residency boundary where a recommended region also exists. Alternate regions help to optimize latency and provide a second region for disaster recovery needs. They are not designed to support Availability Zones (although Azure conducts regular assessment of these regions to determine if they should become recommended regions). These are designated in the Azure portal as Other.
foundational service A core Azure service that is available in all regions when the region is generally available.
mainstream service An Azure service that is available in all recommended regions within 90 days of the region general availability or demand-driven availability in alternate regions.
specialized service An Azure service that is demand-driven availability across regions backed by customized/specialized hardware.
regional service An Azure service that is deployed regionally and enables the customer to specify the region into which the service will be deployed. For a complete list, see Products available by region.
non-regional service An Azure service for which there is no dependency on a specific Azure region. Non-regional services are deployed to two or more regions and if there is a regional failure, the instance of the service in another region continues servicing customers. For a complete list, see Products available by region.

Regions

A region is a set of datacenters deployed within a latency-defined perimeter and connected through a dedicated regional low-latency network. Azure gives you the flexibility to deploy applications where you need to, including across multiple regions to deliver cross-region resiliency. For more information, see Overview of the resiliency pillar.

Availability Zones

An Availability Zone is a high-availability offering that protects your applications and data from datacenter failures. Availability Zones are unique physical locations within an Azure region. Each zone is made up of one or more datacenters equipped with independent power, cooling, and networking. To ensure resiliency, there's a minimum of three separate zones in all enabled regions. The physical separation of Availability Zones within a region protects applications and data from datacenter failures. Zone-redundant services replicate your applications and data across Availability Zones to protect from single-points-of-failure. With Availability Zones, Azure offers industry best 99.99% VM uptime SLA. The full Azure SLA explains the guaranteed availability of Azure as a whole.

An Availability Zone in an Azure region is a combination of a fault domain and an update domain. For example, if you create three or more VMs across three zones in an Azure region, your VMs are effectively distributed across three fault domains and three update domains. The Azure platform recognizes this distribution across update domains to make sure that VMs in different zones are not scheduled to be updated at the same time.

Build high-availability into your application architecture by co-locating your compute, storage, networking, and data resources within a zone and replicating in other zones. Azure services that support Availability Zones fall into two categories:

  • Zonal services – where a resource is pinned to a specific zone (for example, virtual machines, managed disks, Standard IP addresses), or
  • Zone-redundant services – when the Azure platform replicates automatically across zones (for example, zone-redundant storage, SQL Database).

To achieve comprehensive business continuity on Azure, build your application architecture using the combination of Availability Zones with Azure region pairs. You can synchronously replicate your applications and data using Availability Zones within an Azure region for high-availability and asynchronously replicate across Azure regions for disaster recovery protection.

conceptual view of one zone going down in a region

Important

The Availability Zone identifiers (the numbers 1, 2 and 3 in the picture above) are logically mapped to the actual physical zones for each subscription independently. That means that Availability Zone 1 in a given subscription might refer to a different physical zone than Availability Zone 1 in a different subscription. As a consequence, it's recommended to not rely on Availability Zone IDs across different subscriptions for virtual machine placement.

Region and service categories

Azure's approach on availability of Azure services across regions is best described by expressing services made available in recommended regions and alternate regions.

  • Recommended region - A region that provides the broadest range of service capabilities and is designed to support Availability Zones now, or in the future. These are designated in the Azure portal as Recommended.
  • Alternate (other) region - A region that extends Azure's footprint within a data residency boundary where a recommended region also exists. Alternate regions help to optimize latency and provide a second region for disaster recovery needs. They are not designed to support Availability Zones (although Azure conducts regular assessment of these regions to determine if they should become recommended regions). These are designated in the Azure portal as Other.

Comparing region types

Azure services are grouped into three categories: foundational, mainstream, and specialized services. Azure's general policy on deploying services into any given region is primarily driven by region type, service categories, and customer demand:

  • Foundational – Available in all recommended and alternate regions when the region is generally available, or within 90 days of a new foundational service becoming generally available.
  • Mainstream – Available in all recommended regions within 90 days of the region general availability; demand-driven in alternate regions (many are already deployed into a large subset of alternate regions).
  • Specialized – Targeted service offerings, often industry-focused or backed by customized/specialized hardware. Demand-driven availability across regions (many are already deployed into a large subset of recommended regions).

To see which services are deployed in a given region, as well as the future roadmap for preview or general availability of services in a region, see Products available by region.

If a service offering is not available in a specific region, you can share your interest by contacting your Microsoft sales representative.

Region type Non-regional Foundational Mainstream Specialized Availability Zones Data residency
Recommended ✔️ ✔️ ✔️ Demand-driven ✔️ ✔️
Alternate ✔️ ✔️ Demand-driven Demand-driven N/A ✔️

Services by category with Availability Zones

As mentioned previously, Azure classifies services into three categories: foundational, mainstream, and specialized. Service categories are assigned at general availability. Often, services start their lifecycle as a specialized service and as demand and utilization increases may be promoted to mainstream or foundational. The following table lists the category for services as foundational, mainstream. You should note the following about the table:

Foundational Mainstream
Storage Accounts API Management
Application Gateway App Configuration
Azure Backup App Service
Azure Cosmos DB Automation
Azure Data Lake Storage Gen2 Azure Active Directory Domain Services
Azure ExpressRoute Azure Bastion
Azure Public IP Azure Cache for Redis
Azure SQL Database Azure Cognitive Search
Azure SQL : Managed Instance Azure Cognitive Services
Disk Storage Azure Cognitive Services: Computer Vision
Event Hubs Azure Cognitive Services: Content Moderator
Key Vault Azure Cognitive Services: Face
Load balancer Azure Cognitive Services: Immersive Reader
Service Bus Azure Cognitive Services: Language Understanding
Service Fabric Azure Cognitive Services: Speech Services
Storage: Hot/Cool Blob Storage Tiers Azure Cognitive Services: Text Analytics
Storage: Managed Disks Azure Cognitive Services: Translator
Virtual Machine Scale Sets Azure Data Explorer
Virtual Machines Azure Data Share
Virtual Machines: Azure Dedicated Host Azure Database for MySQL
Virtual Machines: Av2-Series Azure Database for PostgreSQL
Virtual Machines: Bs-Series Azure DDoS Protection
Virtual Machines: DSv2-Series Azure Firewall
Virtual Machines: DSv3-Series Azure Firewall Manager
Virtual Machines: Dv2-Series Azure Functions
Virtual Machines: Dv3-Series Azure IoT Hub
Virtual Machines: ESv3-Series Azure Kubernetes Service (AKS)
Virtual Machines: Ev3-Series Azure Machine Learning
Virtual Network Azure Monitor: Application Insights
VPN Gateway Azure Monitor: Log Analytics
Azure Private Link
Azure Red Hat OpenShift
Azure Site Recovery
Azure Stream Analytics
Azure Synapse Analytics
Batch
Cloud Services: M-series
Container Instances
Container Registry
Data Factory
Event Grid
HDInsight
Logic Apps
Media Services
Network Watcher
Notification Hubs
Premium Blob Storage
Premium Files Storage
Virtual Machines: Ddsv4-Series
Virtual Machines: Ddv4-Series
Virtual Machines: Dsv4-Series
Virtual Machines: Dv4-Series
Virtual Machines: Edsv4-Series
Virtual Machines: Edv4-Series
Virtual Machines: Esv4-Series
Virtual Machines: Ev4-Series
Virtual Machines: Fsv2-Series
Virtual Machines: M-Series
Virtual WAN

Specialized Services

As mentioned previously, Azure classifies services into three categories: foundational, mainstream, and specialized. Service categories are assigned at general availability. Often, services start their lifecycle as a specialized service and as demand and utilization increases may be promoted to mainstream or foundational. The following table lists specialized services.

Specialized
Azure API for FHIR
Azure Analysis Services
Azure Cognitive Services: Anomaly Detector
Azure Cognitive Services: Custom Vision
Azure Cognitive Services: Form Recognizer
Azure Cognitive Services: Personalizer
Azure Cognitive Services: QnA Maker
Azure Database for MariaDB
Azure Database Migration Service
Azure Dedicated HSM
Azure Digital Twins
Azure Health Bot
Azure HPC Cache
Azure Lab Services
Azure NetApp Files
Azure SignalR Service
Azure Spring Cloud Service
Azure Time Series Insights
Azure VMware Solution
Azure VMware Solution by CloudSimple
Data Lake Analytics
Azure Machine Learning Studio (classic)
Spatial Anchors
Storage: Archive Storage
Ultra Disk Storage
Video Indexer
Virtual Machines: DASv4-Series
Virtual Machines: DAv4-Series
Virtual Machines: DCsv2-series
Virtual Machines: EASv4-Series
Virtual Machines: EAv4-Series
Virtual Machines: HBv1-Series
Virtual Machines: HBv2-Series
Virtual Machines: HCv1-Series
Virtual Machines: H-Series
Virtual Machines: LSv2-Series
Virtual Machines: Mv2-Series
Virtual Machines: NCv3-Series
Virtual Machines: NDv2-Series
Virtual Machines: NVv3-Series
Virtual Machines: NVv4-Series
Virtual Machines: SAP HANA on Azure Large Instances

Next steps