zone balancing

Zone balancing refers to the automatic distribution of virtual machine instances across Azure availability zones to improve application resilience. Microsoft has introduced automatic zone balancing for Azure Virtual Machine Scale Sets (VMSS) as a public preview feature. This built-in mechanism ensures VMSS instances are evenly spread across zones, reducing the risk that a single zone outage impacts a disproportionate share of an application. The feature uses a create-before-delete rebalancing workflow to minimize disruption to running services. It also includes automatic instance repair by default, adding instance-level health protection on top of zone-level resilience. This capability is designed for cloud operators seeking to enhance fault tolerance and maintain balanced workloads across availability zones.