past paper BYOD vs CYOD

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0. Problem

Explain the differences between BYOD and CYOD, and describe the key features of NAC (Network Access Control) in a wireless LAN environment.

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1. Introduction

① Concepts / Definitions

• BYOD (Bring Your Own Device)
  Policy allowing employees to use their personally owned smartphones, tablets, or laptops for work purposes.
  Device choice, purchase, and ownership remain with the user.

• CYOD (Choose Your Own Device)
  Policy where the organization provides a pre-approved list of devices for employees to choose from.
  Device ownership is usually with the organization, or if owned by the user, it still complies with corporate security standards.

② Historical Background

• BYOD emerged in the early 2010s due to the proliferation of personal mobile devices and remote work trends.
• CYOD evolved to address BYOD’s security and management challenges.

③ Purpose

• BYOD: Reduce costs, improve flexibility, and accommodate user preferences.
• CYOD: Enhance security, simplify device management, ensure regulatory compliance.

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2. Main Body

① BYOD vs CYOD Comparison

Aspect	BYOD	CYOD
Ownership	User	Organization or user (under corporate standards)
Device Choice	Unrestricted	Limited to pre-approved list
Security Control	More difficult (diverse devices/OS)	Easier (standardized devices)
Cost Burden	User	Organization (or shared)
Advantages	Flexibility, lower initial cost for company	Stronger security, easier management
Disadvantages	Higher security risk, complex support	Limited choice, higher initial cost

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② NAC (Network Access Control) in Wireless LAN – Concept

NAC is a security framework that authenticates, authorizes, and enforces policy compliance for devices attempting to connect to a network.
In wireless LAN environments, it often integrates with 802.1X authentication and WPA2/WPA3-Enterprise to provide identity verification, security posture checks, and dynamic access control.

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③ Key Features of Wireless LAN NAC

1. User & Device Authentication

   • Based on 802.1X/EAP protocols.
   • Integrates with AD (Active Directory), LDAP, or RADIUS servers.
   • Applies differentiated policies for BYOD and CYOD devices.

2. Security Posture Assessment

   • Checks for updated antivirus, OS security patches, MDM (Mobile Device Management) enrollment.
   • Non-compliant devices are moved to a quarantine VLAN.

3. Dynamic Policy Enforcement

   • Assigns VLANs or ACLs based on user role, location, and device type.
   • Example: Separate network segments for employees, contractors, and guests.

4. Integration with Wireless Access Points

   • NAC server communicates with APs to allow or block devices.
   • Unauthorized or unauthenticated devices are disconnected automatically.

5. Visibility & Audit

   • Maintains connection logs, MAC/IP history.
   • Detects abnormal traffic and generates alerts.

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④ Practical Examples

• BYOD scenario: NAC allows access only after verifying device security posture and MDM registration.
• CYOD scenario: Pre-configured corporate certificates and security agents enable seamless NAC approval.
• Guest Wi-Fi: Web portal authentication, then internet-only VLAN assignment.

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3. Conclusion

Child-Friendly Summary
BYOD means “I use my own phone or laptop for work.” CYOD means “I choose from a list of devices the company approves.” Wireless NAC is like a gatekeeper that checks who you are and whether your device is safe before letting you on the Wi-Fi.

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One-Glance Summary Table

Item	BYOD	CYOD
Ownership	User	Organization
Choice Freedom	High	Limited
Security Management	Difficult	Easier
Cost to Company	Lower	Higher

NAC Feature	Description
Authentication	802.1X/EAP-based user and device identity check
Security Check	Patch, antivirus, MDM verification
Policy Enforcement	Role/location/device-based VLAN/ACL assignment
AP Integration	Automatic block for unauthorized devices
Visibility	Logs, history, anomaly detection

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