Strong platform grounding to keep designs buildable: next-gen firewalls (Palo Alto, Fortinet), AWS NFW, IDS/IPS, NAC/802.1X, PKI, VPN, ZTNA (Zscaler, Prisma Access, or equivalent), and core protocols (TCP/IP, BGP, OSPF, VLAN, TLS/PKI). Serve as the security design authority for new infrastructure: run design reviews and threat models early enough to change the design, and define the criteria under which a design is approved, conditionally approved, or rejected.