Is there a way to find out how many zones are then per availability zone Region. does it always 3 zones per availability one? Are there regions where there are more than 3 zones per availability zone?
This can help you see the regions:
az account list-locations -o table
According to the cli documentation, it appears there are 3 per region [--zone {1, 2, 3}] as shown below, since it enumerates zones 1, 2, and 3 as options when you do an az vm create command that would include --location and --zone
az vm create --name
--resource-group
[--accelerated-networking {false, true}]
[--admin-password]
[--admin-username]
[--asgs]
[--assign-identity]
[--attach-data-disks]
[--attach-os-disk]
[--authentication-type {all, password, ssh}]
[--availability-set]
[--boot-diagnostics-storage]
[--computer-name]
[--custom-data]
[--data-disk-caching]
[--data-disk-sizes-gb]
[--ephemeral-os-disk {false, true}]
[--generate-ssh-keys]
[--image]
[--license-type {None, Windows_Client, Windows_Server}]
[--location]
[--nics]
[--no-wait]
[--nsg]
[--nsg-rule {RDP, SSH}]
[--os-disk-caching {None, ReadOnly, ReadWrite}]
[--os-disk-name]
[--os-disk-size-gb]
[--os-type {linux, windows}]
[--plan-name]
[--plan-product]
[--plan-promotion-code]
[--plan-publisher]
[--ppg]
[--private-ip-address]
[--public-ip-address]
[--public-ip-address-allocation {dynamic, static}]
[--public-ip-address-dns-name]
[--public-ip-sku {Basic, Standard}]
[--role]
[--scope]
[--secrets]
[--size]
[--ssh-dest-key-path]
[--ssh-key-values]
[--storage-account]
[--storage-container-name]
[--storage-sku]
[--subnet]
[--subnet-address-prefix]
[--subscription]
[--tags]
[--ultra-ssd-enabled {false, true}]
[--use-unmanaged-disk]
[--validate]
[--vnet-address-prefix]
[--vnet-name]
[--zone {1, 2, 3}]
Source: https://learn.microsoft.com/en-us/cli/azure/cloud?view=azure-cli-latest#az-cloud-list ~