If traffic hits the default deny, it means no preceding allow or deny rule matched. Troubleshooting involves checking the criteria of the intended rule and rules above it, and ensuring the firewall has the information needed to evaluate those criteria. - Option A (Correct): If App-Ld doesn't recognize the application, a rule specified with that application's App-ID will not match. This is a common issue with new or custom applications. - Option B (Correct): Decryption failure can impactApp-ID accuracy, especially for distinguishing applications on standard ports like 443. If App-ID relies on seeing content after decryption, and decryption fails, the application might be misidentified or identified as 'unknown', preventing the rule match. - Option C (Correct): If the rule includes a 'Source User' criterion, and User-ID isn't working for that user's session, the rule requiring a specific user or group will not match. The session would likely show 'unknown' user in the logs. - Option D (Correct): Security policy rules are evaluated top-down. A more specific deny rule higher up (e.g., denying access to certain URL categories, source IPs, or applications) could be blocking the traffic before it reaches the intended allow rule. - Option E (Incorrect): The 'Public' zone typically represents the entire internet. Destination IP addresses are evaluated against routing and zones, but the zone definition usually encompasses all public IPs, not requiring specific inclusion of SaaS IPs within the zone itself (though address objects could be used in policies within the zone context).