Questions about Azure Firewall : Number of AZ

Hello @LaurentC ,

Welcome to the Microsoft Q&A forum.

Azure availability zones are physically separate locations within each Azure region that are tolerant to local failures. Failures can range from software and hardware failures to events such as earthquakes, floods, and fires. Tolerance to failures is achieved because of redundancy and logical isolation of Azure services. To ensure resiliency, a minimum of three separate availability zones are present in all availability zone-enabled regions. You can find more information regarding availability zones in this documentation here.

When an Azure Firewall is deployed with two or more availability zones it increases its availability to 99.99% uptime. There's no additional cost for a firewall deployed in more than one Availability Zone. However, there are added costs for inbound and outbound data transfers associated with Availability Zones. You can find more information here.

Based on your question above

i can see in "properties" Azure Firewall, in "Availability zone" : "-"
What does it means ? (please, look in attachment)

I think this indicates that the Azure Firewall was not deployed with Availability Zones.

As Availability Zones can only be configured during deployment. You can't configure an existing firewall to include Availability Zones. If you wish to add availability zones to your Firewall you will have to redeploy it.

Hope this helps answer your query, please let me know if you have any questions here. Thank you!