Abstract

As enterprise networks expand in scale and complexity, ensuring secure and controlled access to resources becomes a critical challenge. Policy-driven network access control (PD-NAC) mechanisms provide a framework for managing user and device access based on predefined security policies, roles, and contextual conditions. Unlike traditional access control approaches that rely solely on static rules, PD-NAC dynamically evaluates access requests using attributes such as user identity, device type, location, and threat intelligence. This approach enhances the security posture of enterprise-scale systems by enforcing consistent policies across heterogeneous environments, including on-premises, cloud, and hybrid infrastructures. This paper investigates the design, implementation, and evaluation of PD-NAC mechanisms for large-scale enterprise networks. Key contributions include the development of adaptive policy frameworks, integration with identity and access management systems, and mechanisms for real-time monitoring and anomaly detection. The study also explores the impact of PD-NAC on network performance, compliance, and operational efficiency. Findings indicate that policy-driven mechanisms improve access control granularity, reduce unauthorized access, and facilitate regulatory compliance, while highlighting trade-offs related to policy complexity and system overhead. The research provides actionable insights for organizations seeking scalable, dynamic, and resilient access control solutions in modern enterprise networks