- A
The default route on the FortiGate is missing
Why wrong: The FortiGate can ping 8.8.8.8, so it has a default route.
- B
The internal hosts have the wrong default gateway configured
If hosts point to a wrong gateway, traffic won't reach the FortiGate.
- C
DNS resolution is failing
Why wrong: Ping uses IP, not DNS. The issue is connectivity, not resolution.
- D
The FortiGate's interface to the internal network is down
Why wrong: If the interface were down, the FortiGate likely wouldn't be able to ping from itself either, but it could still ping if the internal interface is separate? Actually ping from FortiGate uses its own routing, so internal interface down would not affect pinging 8.8.8.8 if default route is via port1. So internal interface could be down and still ping. But then internal hosts wouldn't reach the FortiGate. So this is plausible. However, the most likely is wrong gateway.
Quick Answer
The answer is that the internal hosts have the wrong default gateway configured. This is correct because the FortiGate’s successful ping to 8.8.8.8 confirms its own default route and internet connectivity are working, so the failure must be at the host level. When internal hosts cannot access the internet despite a permissive firewall policy, the traffic is likely not reaching the FortiGate at all—meaning the hosts are sending packets to an incorrect next-hop IP address instead of the FortiGate’s internal interface. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your ability to isolate Layer 3 forwarding issues versus policy or routing failures; a common trap is to immediately suspect NAT or policy misconfiguration when the real problem is host-side default gateway misassignment. Remember the memory tip: “If the gate can ping, but the hosts can’t sing, check the gateway they’re flinging.”
NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 is troubleshooting a connectivity issue. A ping from the FortiGate to 8.8.8.8 succeeds, but traffic from internal hosts to the internet is failing. The firewall policy allows the traffic. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The internal hosts have the wrong default gateway configured
Since the FortiGate can ping 8.8.8.8, its default route and internet connectivity are working. The issue is that internal hosts cannot reach the internet, which points to a Layer 3 forwarding problem at the host level. The most likely cause is that the internal hosts have the wrong default gateway configured, so their traffic is not being sent to the FortiGate for routing.
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.
- ✗
The default route on the FortiGate is missing
Why it's wrong here
The FortiGate can ping 8.8.8.8, so it has a default route.
- ✓
The internal hosts have the wrong default gateway configured
Why this is correct
If hosts point to a wrong gateway, traffic won't reach the FortiGate.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
DNS resolution is failing
Why it's wrong here
Ping uses IP, not DNS. The issue is connectivity, not resolution.
- ✗
The FortiGate's interface to the internal network is down
Why it's wrong here
If the interface were down, the FortiGate likely wouldn't be able to ping from itself either, but it could still ping if the internal interface is separate? Actually ping from FortiGate uses its own routing, so internal interface down would not affect pinging 8.8.8.8 if default route is via port1. So internal interface could be down and still ping. But then internal hosts wouldn't reach the FortiGate. So this is plausible. However, the most likely is wrong gateway.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a successful ping from the FortiGate implies end-to-end connectivity, overlooking that the internal hosts' default gateway configuration is independent of the FortiGate's own routing table.
Detailed technical explanation
How to think about this question
When a host sends traffic to a non-local destination, it checks its routing table for a default gateway; if that gateway is misconfigured (e.g., wrong IP or no gateway set), the host will either send the packet to a non-routing device or drop it. The FortiGate's successful ping to 8.8.8.8 confirms that its own routing (including the default route) and NAT (if used) are functional, isolating the problem to the host-side Layer 3 configuration. In real-world scenarios, this often occurs after DHCP scope changes or static IP misconfigurations where the gateway address is not updated.
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.
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FAQ
Questions learners often ask
What does this NSE4 question test?
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The internal hosts have the wrong default gateway configured — Since the FortiGate can ping 8.8.8.8, its default route and internet connectivity are working. The issue is that internal hosts cannot reach the internet, which points to a Layer 3 forwarding problem at the host level. The most likely cause is that the internal hosts have the wrong default gateway configured, so their traffic is not being sent to the FortiGate for routing.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 24, 2026
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.
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