When deploying multiple VMs in a single availability set via ARM templates you want to maximize how many VMs remain available during fabric failure or maintenance. What value should you set for the platformUpdateDomainCount property?

For an Azure Availability Set, the platformUpdateDomainCount property specifies the number of update domains. Update domains are logical groupings of VMs and underlying hardware that can be rebooted at the same time during planned maintenance. To maximize VM availability during such events, you want to distribute your VMs across as many update domains as possible. The maximum recommended value for platformUpdateDomainCount is 20. While you can technically set it higher, Azure only guarantees the distribution across up to 20 update domains. Setting it to 10 would provide fewer distinct update domains, increasing the risk of multiple VMs being unavailable simultaneously during maintenance. Values like 30 or 40 exceed the practical maximum for effective distribution.