The answer is Block. This is correct because, in FortiGate IPS sensor configurations, the default action for the ICMP Flood anomaly is explicitly set to Block, meaning that when the anomaly threshold is exceeded—as seen in the detected anomalies from 10.1.1.100 to 10.2.2.200—the IPS sensor will automatically drop the offending traffic without requiring manual policy tuning. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this concept tests your understanding of pre-defined anomaly actions within the IPS sensor profile, a common area where candidates mistakenly assume anomalies default to “Monitor” or “Pass.” A frequent trap is confusing ICMP Flood with other flood types like SYN or UDP, which may have different defaults; always verify the specific anomaly name in the sensor settings. Memory tip: ICMP Flood is “Blocked by default”—think of ICMP as a chatty protocol that needs strict enforcement, so Fortinet locks it down from the start.
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.
Exhibit
Refer to the exhibit.
diagnose ips anomaly list
IPS anomalies detected:
1. ICMP Flood from 10.1.1.100 to 10.2.2.200: 5000 pps (threshold: 1000 pps)
2. TCP Scan from 10.1.1.100 to 10.2.2.200: 1000 pps (threshold: 500 pps)
3. UDP Flood from 10.1.1.100 to 10.2.2.200: 3000 pps (threshold: 2000 pps)
An administrator runs the command shown in the exhibit and sees anomalies detected from 10.1.1.100 to 10.2.2.200. The IPS sensor's anomaly settings are configured with the default actions. What will be the default action for the ICMP Flood anomaly?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Block
The correct answer is B because, by default, FortiGate IPS sensors set the action for ICMP Flood anomalies to 'Block'. This default action is defined in the IPS sensor configuration and is applied when the anomaly threshold is exceeded, as indicated by the detected anomalies from 10.1.1.100 to 10.2.2.200.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Monitor
Why it's wrong here
'Monitor' is used for some anomalies but not for flood types.
✓
Block
Why this is correct
Default action for flood anomalies is to block the source.
Related concept
Read the scenario before looking for a memorised answer.
'Quarantine' is not a default action for anomalies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the default action for anomaly-based IPS signatures with the default action for signature-based IPS rules, where 'Monitor' is the default, leading them to incorrectly select 'Monitor' for flood anomalies.
Detailed technical explanation
How to think about this question
In FortiGate IPS sensors, anomaly-based detection uses predefined signatures for flood attacks like ICMP Flood, with default actions set to 'Block' to immediately drop offending packets. The 'Block' action discards the traffic and logs the event, while the administrator can customize actions to 'Monitor' or 'Quarantine' based on policy needs. This default ensures that flood anomalies are mitigated by default, preventing network resource exhaustion without requiring manual configuration.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the NSE4 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Profiles — This question tests Security Profiles — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Block — The correct answer is B because, by default, FortiGate IPS sensors set the action for ICMP Flood anomalies to 'Block'. This default action is defined in the IPS sensor configuration and is applied when the anomaly threshold is exceeded, as indicated by the detected anomalies from 10.1.1.100 to 10.2.2.200.
What should I do if I get this NSE4 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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