What helps avoid split brain in active-passive high availability (HA) pair deployment?

Using the management interface as the HA1 backup link helps avoid split brain in active-passive high availability (HA) pair deployment. High availability (HA) is a feature that provides redundancy and failover protection for firewalls in case of hardware or software failure. Active-passive HA is a mode of HA that consists of two firewalls in a pair, where one firewall is active and handles all traffic, while the other firewall is passive and acts as a backup. Split brain is a condition that occurs when both firewalls in an HA pair assume the active role and start processing traffic independently, resulting in traffic duplication, policy inconsistency, or session disruption. Split brain can be caused by network failures, device failures, or configuration errors that prevent the firewalls from communicating their HA status and synchronizing their configurations and sessions. Using the management interface as the HA1 backup link helps avoid split brain in active-passive HA pair deployment. The HA1 interface is used for exchanging HA state information and configuration synchronization between the firewalls. Using the management interface as the HA1 backup link provides redundancy and failover protection for the HA1 interface, ensuring that the firewalls can maintain their HA communication and avoid split brain. Using a standard traffic interface as the HA2 backup, enabling preemption on both firewalls in the HA pair, or using a standard traffic interface as the HA3 link do not help avoid split brain in active-passive HA pair deployment, but they are related features that can enhance performance and reliability. References: Palo Alto Networks Certified Software Firewall Engineer (PCSFE), [High Availability Overview], [Configure HA Backup Links], [Configure Heartbeat Backup]