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Security Fundamentals & Crypto · Foundational

Network Access Control (NAC)

Technology that authenticates and checks devices before granting network access, enforcing policy at the edge.

Definition

NAC uses 802.1X, MAC Authentication Bypass, and posture assessment to decide whether a device gets full access, limited access, or quarantine. Agent-based NAC installs software for posture checks, while agentless NAC uses scanning and profiling. Cisco ISE, Aruba ClearPass, and Forescout are common products.

Example

A personal laptop plugged into a conference room jack is placed into a guest VLAN.

Exam tip

NAC = who and what is connecting, and is it healthy; it enforces at switch ports and Wi-Fi.

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