What happens when a packet from an existing session is received by a firewall that

When a packet from an existing session is received by a firewall that is part of an HA (High Availability) pair:

D.The firewall takes ownership of the session from the peer firewall

In a high-availability configuration, if a firewall in an HA pair receives a packet for an existing session that it is not currently handling, it will take ownership of that session from the peer firewall. This ensures seamless continuity of the session and maintains the stateful nature of the firewall's session handling.

References:

Palo Alto Networks - High Availability Concepts: https://docs.paloaltonetworks.com/pan-os/10-0/pan-os-admin/high-availability/ha-concepts