Quick Answer
The correct answer is that the sessions have expired and are being cleaned up. When you see 'expire=0' and 'proto_state=01' in the FortiGate session table, it indicates the session has reached its time-to-live limit and is now in a termination state, where the firewall is actively removing the entry from memory. The 'proto_state=01' value specifically represents a TCP session in the cleanup phase, meaning no further traffic will be accepted for that flow, which explains why the administrator observes traffic being dropped from the affected subnet. On the Fortinet NSE 7 Advanced Security exam, this scenario tests your ability to interpret session table flags under real-world troubleshooting conditions, often appearing as a distractor where candidates mistakenly think the session is still active or that a policy is misconfigured. A common trap is confusing 'proto_state=01' with a valid established state, but remember that any state with 'expire=0' is dead. Memory tip: think of '01' as the "one-way out" door—once expire hits zero, the session is out and being swept away.
This NSE7 practice question tests your understanding of troubleshooting and diagnostics. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 observes that traffic from a specific subnet is being dropped by the FortiGate. The session table shows the sessions with 'proto_state=01' and 'expire=0'. What does this indicate?
The sessions have expired and are being cleaned up
Expire=0 means the session has timed out.
The antivirus scanning is causing a delay
Why wrong: Antivirus scanning would not set expire to 0.
The sessions are being offloaded to the NPU
Why wrong: Offloaded sessions would have different flags, not expire=0.
The firewall policy is blocking the traffic
Why wrong: Blocked traffic would not have a session entry.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The sessions have expired and are being cleaned up
Option A is correct. 'expire=0' and 'proto_state=01' indicate that the session has expired and is in a cleanup state. The traffic is being dropped because the session is no longer valid.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The sessions have expired and are being cleaned up
Why this is correct
Expire=0 means the session has timed out.
Related concept
CIDR notation defines the prefix length.
The antivirus scanning is causing a delay
Why it's wrong here
Antivirus scanning would not set expire to 0.
The sessions are being offloaded to the NPU
Why it's wrong here
Offloaded sessions would have different flags, not expire=0.
The firewall policy is blocking the traffic
Why it's wrong here
Blocked traffic would not have a session entry.
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related NSE7 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Troubleshooting and Diagnostics — This question tests Troubleshooting and Diagnostics — CIDR notation defines the prefix length..
The correct answer is: The sessions have expired and are being cleaned up — Option A is correct. 'expire=0' and 'proto_state=01' indicate that the session has expired and is in a cleanup state. The traffic is being dropped because the session is no longer valid.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related NSE7 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 21, 2026
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