Quick Answer
The correct answers are packet length constraints, protocol field matching, and protocol anomaly detection. Custom IPS signatures on FortiGate allow administrators to define precise detection criteria by targeting specific protocol fields, enforcing packet length constraints, and identifying protocol anomalies that deviate from RFC standards, all of which are essential for blocking non-standard traffic without relying on pre-defined signatures. On the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your understanding of the three distinct options available within the custom IPS signature engine, often tripping candidates who mistakenly select application control—a separate feature that operates at a different layer. A common trap is confusing protocol anomaly detection with application control, but remember: custom IPS focuses on low-level protocol behavior, not application identification. Memory tip: think “Fields, Length, Anomaly” as the three pillars of custom IPS signatures.
This NSE7 practice question tests your understanding of advanced threat protection. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A FortiGate administrator wants to detect and block protocol anomalies as part of advanced IPS. Which three options are available in FortiGate's custom IPS signatures? (Choose three.)
Protocol-specific fields
Can specify fields like TCP flags, HTTP headers.
Protocol anomaly detection
Custom signatures can detect anomalies like invalid protocol combinations.
Packet length constraints
Can detect packets with abnormal lengths.
Application signatures
Why wrong: Application signatures are part of application control, not custom IPS signatures.
URL filtering
Why wrong: URL filtering is separate from IPS.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Protocol-specific fields
Correct answers: A, B, D. Custom IPS signatures can target specific protocol fields, packet length, and protocol anomalies. Application control is separate.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Protocol-specific fields
Protocol anomaly detection
Why this is correct
Custom signatures can detect anomalies like invalid protocol combinations.
Related concept
Static NAT maps one inside address to one outside address.
Packet length constraints
Why this is correct
Can detect packets with abnormal lengths.
Related concept
Static NAT maps one inside address to one outside address.
Application signatures
Why it's wrong here
Application signatures are part of application control, not custom IPS signatures.
URL filtering
Why it's wrong here
URL filtering is separate from IPS.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE7 NAT questions on configuration and troubleshooting.
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FAQ
Advanced Threat Protection — This question tests Advanced Threat Protection — Static NAT maps one inside address to one outside address..
The correct answer is: Protocol-specific fields — Correct answers: A, B, D. Custom IPS signatures can target specific protocol fields, packet length, and protocol anomalies. Application control is separate.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE7 NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A FortiGate administrator wants to block a custom protocol anomaly where a client sends an HTTP request with a malformed header containing a null byte. Which advanced IPS feature should be used?
hardWhy D: Protocol Anomaly Detection in the IPS sensor is designed to identify deviations from standard protocol behavior, such as malformed headers or null bytes in HTTP requests. This feature inspects traffic for known protocol violations without requiring custom signatures, making it the correct choice for blocking a null byte anomaly in HTTP headers.
Last reviewed: Jun 21, 2026
This NSE7 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 NSE7 exam.
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