Question 102 of 1,000

Security Profiles →hardMultiple SelectObjective-mapped

Quick Answer

The answer is to check if the firewall policy is using 'flow-based' or 'proxy-based' inspection mode, because some IPS signatures require proxy mode to enforce a 'Block' action. When a signature is set to block but traffic passes through, the inspection mode is often the culprit: flow-based mode processes packets quickly but may skip deep packet inspection for certain complex signatures, whereas proxy-based mode reassembles the full stream, allowing the IPS engine to match and block the traffic as configured. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this question tests your understanding of how IPS inspection modes interact with firewall policies—a common trap is assuming that simply enabling the signature and applying the sensor is enough. The second check is verifying that the IPS sensor is applied to the correct policy direction (incoming or outgoing), as misapplied direction can also prevent blocking. Memory tip: think "Flow for speed, Proxy for depth—if your block won't stick, check the mode quick."

NSE4 Security Profiles Practice Question

This NSE4 practice question tests your understanding of security profiles. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.

An administrator configures an IPS sensor with a signature that is triggered by traffic to a specific server. The signature is set to 'Block' but the traffic is not being blocked. The administrator verifies that the IPS sensor is applied to the correct firewall policy and that the signature is enabled. Which TWO additional checks should the administrator perform? (Choose two.)

Question 1hardmulti select

Read the full NAT/PAT explanation →

A
Ensure that the antivirus profile is not interfering with IPS.
Why wrong: Antivirus and IPS are independent; they do not interfere with each other's actions.
B
Verify that the signature's 'Action' is not overridden by a higher-priority rule in the IPS sensor.
If multiple rules match the same traffic, the highest priority rule's action takes effect. An override with 'Monitor' could prevent blocking.
C
Check if the firewall policy is using 'flow-based' or 'proxy-based' inspection mode. Some IPS signatures require proxy mode.
Certain IPS signatures, especially those requiring protocol decoding, need proxy-based inspection to function correctly. If the policy is in flow mode, the signature may not be applied effectively.
D
Check if the destination server is in the 'Local-in' policy, which may bypass IPS.
Why wrong: IPS is applied to firewall policies, not local-in policies. Traffic to the FortiGate itself is handled differently.
E
Confirm that the signature has a valid CVE ID.
Why wrong: A signature may or may not have a CVE; lack of CVE does not affect its ability to block.

Full breakdown with real-world context →

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

✓

Verify that the signature's 'Action' is not overridden by a higher-priority rule in the IPS sensor.

Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.

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.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Ensure that the antivirus profile is not interfering with IPS.
Why it's wrong here
Antivirus and IPS are independent; they do not interfere with each other's actions.
✓
Verify that the signature's 'Action' is not overridden by a higher-priority rule in the IPS sensor.
Why this is correct
If multiple rules match the same traffic, the highest priority rule's action takes effect. An override with 'Monitor' could prevent blocking.
Related concept
Static NAT maps one inside address to one outside address.
✓
Check if the firewall policy is using 'flow-based' or 'proxy-based' inspection mode. Some IPS signatures require proxy mode.
Why this is correct
Certain IPS signatures, especially those requiring protocol decoding, need proxy-based inspection to function correctly. If the policy is in flow mode, the signature may not be applied effectively.
Related concept
Static NAT maps one inside address to one outside address.
✗
Check if the destination server is in the 'Local-in' policy, which may bypass IPS.
Why it's wrong here
IPS is applied to firewall policies, not local-in policies. Traffic to the FortiGate itself is handled differently.
✗
Confirm that the signature has a valid CVE ID.
Why it's wrong here
A signature may or may not have a CVE; lack of CVE does not affect its ability to block.

Common exam traps

Common exam trap: NAT rules depend on direction and matching traffic

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

How to think about this question

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.

KKey Concepts to Remember

Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.

TExam Day Tips

Identify inside and outside interfaces first.
Check whether the scenario needs static NAT, dynamic NAT or PAT.
Do not confuse NAT matching ACLs with normal packet-filtering intent.

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

How this comes up in practice

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

Got this wrong? Here's your next step.

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 NSE4 NAT questions on configuration and troubleshooting.

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FAQ

Questions learners often ask

What does this NSE4 question test?

Security Profiles — This question tests Security Profiles — Static NAT maps one inside address to one outside address..

What is the correct answer to this question?

The correct answer is: Verify that the signature's 'Action' is not overridden by a higher-priority rule in the IPS sensor.

What should I do if I get this NSE4 question wrong?

What is the key concept behind this question?

Static NAT maps one inside address to one outside address.

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