Palo Alto Networks reference architecture, modern data center, virtualized infrastructure, cloud security, network security gateway, firewall, intrusion prevention system, advanced threat detection, URL filtering, anti-malware protection, scalable design, high availability, load balancing, clustering, redundant systems, rack-mounted servers, blinking LED lights, sleek metal casing, intricate cable management, air conditioning vents, raised flooring, dimly lit data center room, panoramic view, softbox lighting, 3/4 composition.