Azure Regions, Availability Zones, Availability Set and Scale Set in Azure Cloud

In this blog, we will see about Regions, Regions, Availability Zones, Availability Set and Scale Set available in Azure Cloud.

All these are very important for AZ 900 exam.

Azure Regions

Region is basically a Geographical location.
Azure provides 60+ regions across the Globe.

Benefits of Multiple Azure Regions –

  • High Availability
  • Low Latency
  • Data Redundancy

Availability Zones

Azure provides multiple Availability Zones in a Region.
Each Availability Zones consists of one or more data center.
Each Availability Zones has their own power source and connectivity.
Availability Zones in a region are connected with low latency link.

Not all Azure regions have Availability Zones.

Availability Zones region wise –

  • East US – 3
  • West Europe – 3
  • Southeast Asia – 3
  • West Central Us – 0

Availability Zones provides below advantages –

  • High Availability
  • Low Latency
  • Global Deployment

Availability Set

Availability Set is a logical grouping of Virtual Machines in Azure.
Azure provides 2 types of Availability Set –

  • Fault Domain – It is a group of Virtual Machines which share common power sources and same network.
  • Updated Domain – It is a group of Virtual Machines that do below activities at the same time – Reboot, Maintenance, Update

To get maximum availability, deploy Virtual Machines across multiple Fault Domain.

Scale Set

Scale Set allows you to manage and create a group of Azure Virtual Machines.
It supports manual and auto scaling.
Azure allows up to 1000 VM instances in a single Scale Set.
Auto scaling of VM Scale Set can be set based on multiple parameters –

  • CPU Threshold (%)
  • Memory Utilization

Scale Set also decide how many no. of instances to increase or decrease and for how long.

Types of Scaling in Azure

Azure offers 2 types of scaling –

  • Vertical Scaling – Vertical scaling means, changes in hardware resources. For example – Increase in RAM size. In Vertical Scaling there is a limit, beyond that you can not increase any resource.
  • Horizontal Scaling – Instead of increasing hardware resources, in Horizontal Scaling, Azure allows to increase the number of VMs itself. Example – You can deploy multiple VM instances based on requirement.

Vertical Scaling is expensive compare to Horizontal Scaling. Horizontal scaling is more suitable in case of high availability.


Cloud services is basically means to high availability. Availability is the percentage (%) of time a system is up and running.

If you create a VM instance in Azure, it has % availability on below factors.

  • Single VM with premium SSD = 99.9% Availability
  • Single VM with standard SSD = 99.5%Availability
  • Single VM with standard HDD = 95%Availability
  • Create 2 VM instances in same Availability set = 99.95%Availability

99.95% availability means 22 minutes down time in a single month.

99.99% availability is also called four 9’s availability

Hope you like this blog.

Note: Topic covered in this article are important for AZ-900 Exam
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