For optimal zero-day threat prevention using WildFire, the best approach is to maximize the scope of analysis and automate the response. Enabling WildFire submission for all supported file types ensures that no potential threat vector is missed, as malware can be embedded in a wide variety of files. Setting the action to "block" for high-risk verdicts (such as 'malicious' or 'grayware') is critical for prevention. This configuration allows the firewall to automatically stop the delivery of a file as soon as WildFire identifies it as a threat, effectively preventing the initial compromise and subsequent spread across the network. This proactive and comprehensive strategy provides the most robust security posture.

A. Limiting analysis to only PDF and EXE files creates significant security gaps, as zero-day threats are frequently delivered through other vectors like Microsoft Office documents, scripts, and archives.

B. Disabling WildFire submission completely negates the purpose of the service, which is to analyze unknown files to discover and prevent new, zero-day threats.

C. While per-policy configuration is possible, best practice for optimal security is to apply a consistent and strong WildFire analysis profile broadly to all relevant traffic, ensuring uniform protection.

1. Palo Alto Networks PAN-OS® Administrator’s Guide 10.2

Section: WildFire Analysis Profiles

Content: The guide details the configuration of WildFire Analysis Profiles, stating: "For the broadest coverage, Palo Alto Networks recommends that you forward all unknown files to WildFire for analysis." It also describes setting the Action for each verdict (malicious, grayware, phishing, benign), with 'block' being the preventative option. This directly supports forwarding all types and blocking threats.

2. Palo Alto Networks WildFire® Administrator’s Guide 10.2

Section: Set Up and Manage WildFire > Configure WildFire Analysis

Content: This document explicitly recommends, "To get the most out of your WildFire subscription, create a WildFire Analysis security profile that forwards all unknown files and email links to the WildFire cloud for analysis." This reinforces the principle of comprehensive file submission for optimal security.

3. Palo Alto Networks Technical Documentation - "Best Practice: Create a WildFire Analysis Profile"

Section: Best Practice Internet Gateway WildFire Analysis Profile

Content: This best practice guide advises: "For the best security, forward all file types to WildFire for analysis." and for the Rules section of the profile, it recommends setting the Action for malicious and grayware verdicts to block. This provides a clear, prescriptive model that aligns perfectly with the correct answer.