Availability Zone
A physically separate datacenter within an Azure region, each with independent power, cooling, and networking, used to distribute VMs so a single datacenter failure doesn't take down an entire application.
Availability Zone
Availability Zones give you resilience against an entire datacenter going offline — each zone is physically isolated within the region.
Why It Matters in Production
Hotstar spreads its live-streaming ingest VMs across three Availability Zones in Central India, so a zone-level outage during an IPL final only removes a third of capacity instead of everything.
az vm create --resource-group hotstar-prod-rg --name ingest-vm-01 \ --zone 1 --image Ubuntu2204 --size Standard_D4s_v5TipNot all Azure regions support Availability Zones — check regional zone support before designing a zone-redundant architecture.
Frequently Asked Questions
How many Availability Zones does a typical Azure region have, and does every region support them?
Most Azure regions that support Availability Zones have three, each with independent power, cooling, and networking, connected by low-latency, high-throughput fiber. Not every Azure region supports zones — smaller or newer regions may not — so zone-redundant architecture is only possible where the region explicitly offers zone support, which needs to be checked before designing for it.
What's a common mistake when architecting for Availability Zones?
Deploying VMs across zones but leaving a dependency — like a single-zone database or a non-zone-redundant storage account — as the one component that isn't spread across zones, so the whole system still has a single point of failure. True zone resilience requires every tier of the stack (compute, data, load balancing) to be zone-redundant, not just the easiest layer to configure.