The answer is that the session is initiating a TCP connection and has not yet completed the three-way handshake. This is indicated by proto_state=01, which corresponds to the TCP SYN_SENT state, meaning the client has sent a SYN packet but has not yet received a SYN-ACK from the server. The protocol number 6 confirms TCP, and the combination of a 3600-second duration with an expiring timer shows the session is still in the early establishment phase. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this output from the diagnose sys session filter command tests your ability to interpret session state fields, particularly when filtering by destination port like dport 443. A common trap is confusing proto_state=01 with an established connection; remember that state 01 is the very first step, not a completed handshake. For a quick memory tip, think of “01” as the “one” SYN that has been sent but not yet answered.
NSE4 High Availability and Diagnostics Practice Question
This NSE4 practice question tests your understanding of high availability and diagnostics. 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.
You run 'diagnose sys session filter dport 443' and see the following output:
proto=6 proto_state=01 duration=3600 expire=3599
What does this indicate about the session?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The session is initiating a TCP connection and has not yet completed the handshake
proto_state=01 means TCP SYN_SENT state, meaning the three-way handshake is incomplete. The session is still establishing.
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 session has expired and will be removed in 1 second
Why it's wrong here
expire=3599 means 3599 seconds remaining, not 1 second.
✗
The session is closing and has 3599 seconds until the entry is removed
Why it's wrong here
proto_state=01 is not a closing state; closing states are higher numbers.
✓
The session is initiating a TCP connection and has not yet completed the handshake
Why this is correct
proto_state=01 indicates SYN_SENT, meaning the session is still in the handshake phase.
Related concept
Read the scenario before looking for a memorised answer.
✗
The session is fully established and has been active for 3600 seconds
Why it's wrong here
Established TCP sessions typically show proto_state=02 (ESTABLISHED).
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
Established TCP sessions typically show proto_state=02 (ESTABLISHED).
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 NSE4 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
High Availability and Diagnostics — This question tests High Availability and Diagnostics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The session is initiating a TCP connection and has not yet completed the handshake — proto_state=01 means TCP SYN_SENT state, meaning the three-way handshake is incomplete. The session is still establishing.
What should I do if I get this NSE4 question wrong?
Identify which NSE4 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. You run 'diagnose sys session filter dport 443' and see the following output:
proto=6 proto_state=01 duration=3600 expire=3599
What does this indicate about the session?
hard
A.The session is using UDP protocol
B.The session has expired and is being removed
✓ C.The session is in the TCP SYN sent state, not yet fully established
D.The session has completed the three-way handshake and is established
Why C: The output shows a TCP session (proto=6) in state 01 (TCP SYN sent), duration 3600 seconds, and expire 3599 seconds. This indicates the session is in the initial SYN state and has not completed the three-way handshake.
Variation 2. You run 'diagnose sys session filter dport 443' and see the following output:
proto=6 proto_state=01 duration=3600 expire=3599
What does this indicate?
hard
A.The session is a UDP connection to port 443
B.The session will expire in 3600 seconds
C.The session has been established for 3600 seconds
✓ D.The TCP three-way handshake is incomplete; only SYN was sent
Why D: protocol 6 is TCP. proto_state=01 means TCP SYN_SENT. The session duration is 3600 seconds, expire 3599 seconds left.
Last reviewed: Jun 21, 2026
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.