hardMultiple SelectObjective-mapped
ISC2 CC Practice Question: A network administrator is implementing a…
A network administrator is implementing a defense-in-depth strategy. Which THREE of the following are considered network security controls? (Select THREE)
⚠ Common exam trap
ISC2 often tests the distinction between network-layer controls (VPN, IDS, firewall) and host/endpoint controls (disk encryption, antivirus), so the trap is that candidates mistakenly classify host-based security measures as network security controls.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Virtual Private Network (VPN)
A Virtual Private Network (VPN) is a network security control because it creates an encrypted tunnel (using protocols such as IPsec or TLS) between a remote user and the corporate network, ensuring data confidentiality and integrity over untrusted networks like the internet. This protects data in transit and authenticates endpoints, which is a core network-layer security function.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Virtual Private Network (VPN)
Why this is correct
VPN provides encrypted tunnels for secure communication over untrusted networks, a network security control.
- ✓
Intrusion Detection System (IDS)
Why this is correct
IDS monitors network traffic for malicious activity, making it a network security control.
- ✗
Full disk encryption
Why it's wrong here
Full disk encryption protects data at rest on endpoints, not the network.
- ✓
Network firewall
Why this is correct
A network firewall filters traffic between networks and is a fundamental network security control.
- ✗
Antivirus software
Why it's wrong here
Antivirus is an endpoint security control, not a network control.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
Go deeper
Related to this question
Learn chapter
Introduction to Security Principles
Key term
Integrity
Integrity is the assurance that data has not been altered or tampered with in an unauthorized way, preserving its accuracy and consistency from source to destination.
Key term
Terminal Access Controller Access Control System Plus
TACACS+ is a network security protocol that separates authentication, authorization, and accounting to control who can access network devices and what they can do.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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