This special issue titled “Advances in Discrete Mathematics and Secure Network Technologies”, brings together a diverse and timely collection of research papers that highlight the strong convergence of discrete mathematics, combinatorial theory, cryptography, biometrics, and modern network security. The contributions span foundational mathematical constructs - such as graph theory, combinatorial numbers, algebraic functions, and discrete algorithms - to applied innovations in secure communication, IoT authentication, wireless sensor networks, cryptographic optimization, and zero trust architectures. Several papers explore advanced security mechanisms, including biometric authentication, RSA enhancements, elliptic curve cryptanalysis, and  bio-inspired and AI-driven encryption techniques, addressing the growing complexity of cyber threats in real-time and intelligent networked environments. Collectively, these works demonstrate how rigorous mathematical modeling and combinatorial approaches can drive practical solutions for secure systems, resilient networks, and trustworthy digital infrastructures, making this compilation a valuable source for researchers, academicians, and practitioners alike.