Comprehensive and Detailed In-Depth Step-by-Step Explanation:The Palo Alto Networks Systems Engineer Professional - Software Firewall documentation, particularly the reference architectures for VM-Series firewalls in public cloud environments (e.g., AWS, Azure, GCP), provides best practices for securing deployments. By default, PAN-OS includes predefined security rules like the interzone-default and intrazone-default rules, which need adjustment to enhance security in cloud settings.

Interzone-default rule action and logging (Option C): In PAN-OS, the interzone-default rule is applied to traffic between different security zones (e.g., traffic between a public cloud subnet and an on-premises network). By default, this rule allows all traffic with logging enabled, which can pose a security risk in public cloud environments where traffic should be restricted by default. The reference architecture recommends overriding this rule to deny all interzone traffic by default (changing the action from “allow” to “deny”) and enabling logging to monitor and control traffic more securely. This aligns with the principle of least privilege and enhances security for VM-Series deployments in public clouds, as outlined in the documentation’s security best practices.

Options A (Intrazone-default rule action and logging), B (Intrazone-default rule service), and D (Interzone-default rule service) are incorrect. The intrazone-default rule applies to traffic within the same security zone and typically allows traffic by default, but it is less critical to override in public cloud deployments compared to the interzone rule, as intrazone traffic is often trusted. Changing the “service” (Options B, D) rather than the action and logging is not the primary focus for enhancing security; the action (allow/deny) and logging configuration are more significant for securing traffic flows in VM-Series deployments.

References: Palo Alto Networks Systems Engineer Professional - Software Firewall, Section: VM-Series Reference Architectures, PAN-OS Security Policy Guide, Public Cloud Security Best Practices.