Advanced security testing skills: designing threat-informed test cases, validating encryption/authentication, testing firewall behaviors (DMZ, SNAT/DNAT), conducting exploit validation, and collaborating on vulnerability remediation. Knowledge and Skills: In-depth knowledge of networking protocols and architectures: TCP/IP, IPv4/IPv6, OSPF, BGP, EVPN/VxLAN, MPLS, VLANs, NAT, DHCP, DNS, and real-world deployment patterns.