Azure VM - Update Domain and Fault Domain in Avaibility set

Question

I am reading about availability set in Azure Virtual Machine. And it seems a bit confusing to me.

I have few questions, would appreciate if someone can answer that.

1. Microsoft document says with two or more machines in availability set gives 99.95% availability. if this is the case why they have 3 maximum Fault Domain and 20 maximum Update domain. if I choose a max of both would I get more availability than 99.95%? if not, what is the purpose of having more updates or fault domains than 2?
2. If I have 3 fault domain and 20 update domain, how many physical machines will be created? 20 max(update_domain, fault_domain) or 23 (update_domain + fault_domain)
3. can it be possible to have less number of update domain than fault domain? i.e. 2?

Answer 1

1. no, you would not get a higher SLA, but in theory the more FD\UD you have the more reliable your VMs are (and its free of charge, so no point in having less, tbh)
2. physical machines are not going to be created (how??), but your vms would be split along 20 hypervisors and those hypervisors will be split between 3 fault domains (racks)
3. I dont see why not, but I dont see why would you want to do that.