Support for High Availability on VM-Series on Azure

Traditional HA configuration is not relevant in Azure. For HA, use cloud-native load balancers such as the Azure Application Gateway.
VM-Series on Azure does not support the traditional active/passive high availability with session synchronization, as it is not a good fit for the public cloud architecture where you don’t need to protect against hardware failures (CPU, memory, NIC, HDD) like you would in a private cloud deployment. Instead, for both small and large deployments, use a scale out architecture using cloud-native load balancers such as the Azure Application Gateway or Azure Load Balancer to distribute traffic across a set of healthy instances of the firewall. For details, For details, see Deploy the VM-Series and Azure Application Gateway Template.

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