Hi @Assaf L ,
Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
I understand that you would like to know about the instance manual and autoscaling with respect to Zone-redundant app gateway.
Since we are discussing Zones, I take it that we are considering V2 and V2 WAF Application gateway.
Please correct me if this is wrong.
Now, with V2 and V2 WAF, customers are not charged for instance count, rather for the Capacity units.
This is explained in Understanding Pricing for Azure Application Gateway and Web Application Firewall
Now, to answer your question,
If you are to manually set the instance count to a number X, then you will have only X instances in the backend.
In the example you have mentioned with 3 Zones and 2 Instance,
- You will have only 2 instances.
- We will not have the visibility to know which two Zones these instances spawned.
- However, the internal algorithm makes sure that the instances are evenly distributed across the Zones
I hope this helps.
Please let us know should you have additional queries on this
Thanks,
Kapil
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