High availability (HA) is a deployment in which two firewalls are placed in a group and their configuration is synchronized to prevent a single point of failure on your network. A heartbeat connection between the firewall peers ensures seamless failover in the event that a peer goes down. Setting up two firewalls in an HA pair provides redundancy and allows you to ensure business continuity.
Palo Alto Networks firewalls support stateful active/passive or active/active high availability with session and configuration synchronization with a few exceptions:
The PA-200 firewall supports HA Lite only. The VM-Series firewall in AWS supports active/passive HA only; if it is deployed with Amazon Elastic Load Balancing (ELB), it does not support HA (in this case ELB provides the failover capabilities). The VM-Series firewall in Microsoft Azure does not support HA.
The following topics provide more information about high availability and how to configure it in your environment.

Related Documentation