NSE4 Security Profiles Practice Question
A FortiGate administrator wants to block all traffic to a known malicious IP address range using the Intrusion Prevention System (IPS). Which IPS configuration method is most appropriate?
⚠ Common exam trap
Many candidates confuse IPS anomaly detection (which blocks based on traffic patterns) with the ability to block specific IPs, or assume predefined signatures cover all threats including IP-based blocks, when in fact custom signatures are required for IP-specific filtering.
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
✓
Create a custom IPS signature that matches the IP range
FortiGate's IPS allows administrators to create custom signatures that can match specific IP addresses or ranges using the 'source-ip' or 'destination-ip' filter criteria. This is the most direct and precise method to block traffic to a known malicious IP range, as predefined signatures typically target application-layer vulnerabilities or exploit patterns, not arbitrary IP addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a predefined IPS signature for known malicious IPs
Why it's wrong here
Predefined IPS signatures are designed to detect and block known application-layer threats and exploits, not arbitrary IP addresses or ranges. Therefore, they cannot be used to block a specific malicious IP range.
- ✓
Create a custom IPS signature that matches the IP range
Why this is correct
Creating a custom IPS signature allows specifying source or destination IP addresses or ranges using filters like 'source-ip' or 'destination-ip', making it the most direct method to block traffic to a known malicious IP range.
- ✗
Configure an IPS anomaly detection rule to block the IP range
Why it's wrong here
IPS anomaly detection rules detect deviations from normal traffic patterns (e.g., floods or scans) and are not designed to block specific IP addresses. They are inappropriate for blocking a known malicious IP range.
- ✗
Use a local IPS signature database
Why it's wrong here
The local IPS signature database is a collection of signatures (predefined and custom) but is not a configuration method. Simply using the database does not enable blocking; a custom signature must be created and enabled.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE4 practice question is part of Courseiva's free Fortinet certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NSE4 exam.