Traffic is directed to a Palo Alto Networks firewall integrated with Cisco ACI through a policy-based redirect (PBR). PBR is a method that allows specific traffic to be rerouted based on policies rather than destination IP address alone, making it suitable for directing traffic to security devices like firewalls.

The correct protocol used for communicating between VM-Series firewalls and a gateway load balancer in Amazon Web Services (AWS) is Geneve. Geneve (Generic Network Virtualization Encapsulation) is specifically designed to support the needs of network virtualization and provides greater flexibility and extensibility compared to other protocols.

To enable security orchestration in a software-defined network (SDN), the Palo Alto Networks platform architecture relies on specific elements. A full set of APIs allows for programmatic control of policy and configuration, which is essential for integrating and automating security measures within an SDN environment. Additionally, Dynamic Address Groups enable security policies to be adapted dynamically, responding to changes in the network and ensuring that policies remain effective as the network evolves. These two elements together facilitate comprehensive and flexible security orchestration within an SDN.

Security profiles scan for threats in allowed traffic. They are applied to traffic after it has been allowed by the security policy rule, performing checks for malicious activity or content even in permitted traffic flows.

The deployment modes of VM-Series firewalls that are supported across NSX-T are 'Service Cluster' and 'Host-based.' These deployment modes align with the supported configurations and operational setups for integrating VM-Series firewalls within an NSX-T environment.