Azure availability zones confusion

Question

Hi, I'm Luis. I'm actually training for AZ104 certifications and I get confused by availability zones :

First question ;

Are availability zones distinct datacenters ? For example, in the Region East US, availability zones are enabled. Does that mean there are dedicated datacenters for the purpose of availability zones apart from "primary" datacenters ?

Second question :

If I select I select availability zones 1, does that mean, if a create a VM, that it will be automatically replicated to another datacenter ?

Thank you... this is driving me crazy!

Answer 1

Hi @Luis Bernardo .

Regarding 1: An Availabilty Zone in Azure "contains" one or multiple Azure datacenter(s).

Regarding 2: What is your definition of "primary datacenter"? If you create a VM in one Availability Zone, for instance in Zone 1, only one VM will be created -> in Zone 1. Period.

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten

Answer 2

The MS definition for availability zones is: "Availability Zones are unique physical locations within an Azure region"

This was my initial question: are availability zones special data centers isolated from the others ? How can you achieve 99.99% SLA if not?

Some people say Yes, some No. Who's right?

What's the point? In my second post, you can see in the screenshot that I can only choose ONE between the 3 Availability Zones.

In this article they talk about primary data center:

Answer 3

@srbhatta-MSFT

I took a course on Udemy before passing AZ900.

In this course it says if I choose one AV Z. My VM will be replicated in a dedicated datacenter =>

What I understand is :

• I deploy a VM without any availability zone:

=> the VM is deployed in a datacenter who is not part of an availability zone. (in the diagram, the top datacenters, "Datacenters hors zones de disponibilité"). And if the datacenter fails, I lose de VM.

• I deploy a VM with one availability zone :

=> the VM is deployed in a datacenter who is not part of an availability zone AND in another datacenter who is part of an availability zone (in the diagram, the bottom datacenters, "datacenters zones de disponibilité").

Is this correct ? Is the course "wrong" ?

Thank you very much for your time...