The answer is that the HTTP server is not properly closing connections, causing the FortiGate to wait for a FIN from the client. This is correct because TCP state 11 (TCP_CLOSE_WAIT) indicates the FortiGate has received a FIN from the WAN-side server but is still waiting for the client on the internal side to send its FIN, leaving the session half-open. On the Fortinet NSE 7 Advanced Security NSE7 exam, this scenario tests your understanding of TCP state transitions under a real-world antivirus profile, where the common trap is blaming the antivirus scanning itself for the slow HTTP throughput rather than the accumulated sessions consuming session table resources. Remember that the antivirus profile is not the direct cause—the performance issue stems from incomplete TCP teardown. A useful memory tip: CLOSE_WAIT means the server said “I’m done,” but the client hasn’t said “goodbye.”
NSE7 Enterprise Firewall and VDOMs Practice Question
This NSE7 practice question tests your understanding of enterprise firewall and vdoms. 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.
A FortiGate VDOM is configured with a WAN interface (port1) and LAN interface (internal). The admin creates a policy allowing HTTP from internal to WAN with an antivirus profile applied. Users report that HTTP throughput is very slow. The admin checks the session table and sees many sessions with state 11 (TCP_CLOSE_WAIT). What is causing the performance issue?
The antivirus profile is performing file scanning, causing delays
Why wrong: Antivirus scanning can introduce latency, but it doesn't cause CLOSE_WAIT.
B
The policy is missing a timeout setting for TCP half-close
Why wrong: Not a typical cause.
C
The HTTP server is not properly closing connections, and the FortiGate is waiting for FIN from client
CLOSE_WAIT means the server has closed the connection (FIN received) but the client hasn't. The FortiGate waits for the client's FIN and holds the session.
D
The FortiGate is using proxy-based inspection, which delays session closure
Why wrong: Proxy mode doesn't inherently cause CLOSE_WAIT.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The HTTP server is not properly closing connections, and the FortiGate is waiting for FIN from client
State 11 (TCP_CLOSE_WAIT) indicates that the FortiGate has received a FIN from the server (WAN side) and is waiting for a FIN from the client (internal side) to complete the TCP connection closure. When the HTTP server does not properly close connections, the FortiGate holds these sessions open, consuming session table resources and causing performance degradation. The antivirus profile is not the direct cause; the issue is the accumulation of sessions stuck in CLOSE_WAIT due to incomplete TCP teardown.
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 antivirus profile is performing file scanning, causing delays
Why it's wrong here
Antivirus scanning can introduce latency, but it doesn't cause CLOSE_WAIT.
✗
The policy is missing a timeout setting for TCP half-close
Why it's wrong here
Not a typical cause.
✓
The HTTP server is not properly closing connections, and the FortiGate is waiting for FIN from client
Why this is correct
CLOSE_WAIT means the server has closed the connection (FIN received) but the client hasn't. The FortiGate waits for the client's FIN and holds the session.
Related concept
Read the scenario before looking for a memorised answer.
✗
The FortiGate is using proxy-based inspection, which delays session closure
Why it's wrong here
Proxy mode doesn't inherently cause CLOSE_WAIT.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often attribute slow throughput to antivirus scanning (Option A) or proxy inspection (Option D), but the session state TCP_CLOSE_WAIT directly points to a TCP closure problem, not a content inspection issue.
Detailed technical explanation
How to think about this question
In TCP, CLOSE_WAIT occurs when the local endpoint (FortiGate) receives a FIN from the remote server and acknowledges it, but the local application (or client) has not yet issued its own close. The FortiGate's session table tracks this state; if the client never sends FIN (e.g., due to keep-alive or poor HTTP implementation), sessions accumulate, exhausting the session table and degrading throughput. This is a common issue with HTTP/1.1 persistent connections where the server closes the connection prematurely or the client does not properly handle the teardown.
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 NSE7 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.
Enterprise Firewall and VDOMs — This question tests Enterprise Firewall and VDOMs — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The HTTP server is not properly closing connections, and the FortiGate is waiting for FIN from client — State 11 (TCP_CLOSE_WAIT) indicates that the FortiGate has received a FIN from the server (WAN side) and is waiting for a FIN from the client (internal side) to complete the TCP connection closure. When the HTTP server does not properly close connections, the FortiGate holds these sessions open, consuming session table resources and causing performance degradation. The antivirus profile is not the direct cause; the issue is the accumulation of sessions stuck in CLOSE_WAIT due to incomplete TCP teardown.
What should I do if I get this NSE7 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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