\begin{abstract}
This paper provides a comprehensive review of secured network infrastructure, encompassing fundamental networking concepts, prevalent cyber threats, and advanced defense mechanisms. this study elucidates the evolution of network security from basic packet filtering firewalls to sophisticated Next-Generation Firewalls (NGFWs), Intrusion Detection and Prevention Systems (IDS/IPS), and Virtual Private Networks (VPNs). It further examines various network topologies, routing protocols, and the role of modern simulation tools like Packet Tracer and GNS3 in understanding network behavior and vulnerabilities. The paper categorizes common network attacks such as Denial of Service (DoS), Man-in-the-Middle (MitM), SQL Injection, and Zero-Day Exploits, highlighting their impact on network integrity and availability. The objective is to synthesize this information into a cohesive framework that underscores the critical importance of a multi-layered security approach in safeguarding contemporary digital environments. This review aims to serve as a foundational resource for researchers and practitioners seeking to understand and implement robust network security strategies against an ever-evolving threat landscape. In doing so, it aligns with global sustainable development efforts by reinforcing the resilience and reliability of digital infrastructure essential for sustainable industry and innovation.
\end{abstract}
\begin{IEEEkeywords}
network security, secured network infrastructure, cyber threats, NGFW, IDS/IPS, VPN, DoS/DDoS, Zero Trust, AI/ML security
\end{IEEEkeywords}