hardMultiple Choice
ISC2 CC Practice Question: A security team discovers that an internal…
A security team discovers that an internal database server is sending large amounts of data to an unknown external IP address. The server is not supposed to communicate externally. Which security control should be implemented to prevent such data exfiltration?
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
✓
Configure a firewall to deny all outbound traffic from the database server except to specific authorized destinations
A firewall with restrictive egress rules blocks unauthorized outbound traffic, preventing data exfiltration. Option A (VPN) would not stop the traffic; it could even encrypt and tunnel it. Option B (IDS) can detect but not block. Option D (DLP) monitors content but may not effectively block at the network level.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Implement a VPN for all external communications
Why it's wrong here
A VPN encrypts and tunnels permitted external communications; it does not deny traffic to unknown destinations, so the server could still reach the external IP through the tunnel. It is tempting because VPNs secure remote connectivity, which suits protecting legitimate external links rather than blocking an internal server's outbound traffic.
- ✗
Install an intrusion detection system (IDS) on the network segment
Why it's wrong here
An IDS only detects and alerts on suspicious traffic; it sits passively and cannot block the outbound connection, so exfiltration continues. It is tempting because it monitors network segments for malicious activity, which suits visibility and alerting scenarios rather than actively preventing the data transfer.
- ✓
Configure a firewall to deny all outbound traffic from the database server except to specific authorized destinations
Why this is correct
An outbound deny-by-default rule with explicit allow-listing stops the server reaching unknown external IPs while permitting legitimate destinations. This blocks the exfiltration channel itself, unlike monitoring or inbound filtering, which would not prevent data leaving the internal database server.
- ✗
Deploy a data loss prevention (DLP) system on the server
Why it's wrong here
A DLP system inspects content and blocks sensitive data leaving through monitored channels such as email or endpoints; it does not filter outbound network traffic by destination IP. It is tempting because DLP targets exfiltration directly, which suits preventing sensitive data leaving via user channels rather than a server's unauthorised connections.
Go deeper
Related to this question
Learn chapter
Secure Network Architecture and Design
Key term
IDS
An IDS is a security system that monitors network or system traffic for suspicious activity and alerts administrators to potential threats, but does not actively block them.
Key term
Security control
A security control is a safeguard or countermeasure designed to protect the confidentiality, integrity, and availability of information systems and data.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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