NSE7 Troubleshooting and Diagnostics Practice Question
A FortiGate administrator notices that after upgrading the firmware, some BGP sessions to a service provider are flapping. The administrator runs 'diagnose ip router bgp all' and sees that the BGP neighbor state is Active. What is the MOST likely cause of this issue?
⚠ Common exam trap
The trap here is that candidates often associate the Active state with reachability issues (Option C) or authentication failures (Option D), but in FortiGate, the Active state specifically indicates that the TCP connection is up and the BGP open message is being exchanged, making a configuration mismatch the most likely cause after an upgrade.
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
✓
A configuration checksum mismatch between the two peers
After a firmware upgrade, a BGP session stuck in the Active state is most commonly caused by a configuration checksum mismatch between the two peers. FortiGate uses a BGP configuration checksum to ensure that both sides have identical BGP configurations; if the checksums do not match after an upgrade (e.g., due to a change in default parameters or a new feature), the session will not establish and will remain in Active. This is a known behavior in FortiOS where the checksum is compared during the BGP open message exchange, and a mismatch prevents the session from moving to Established.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A configuration checksum mismatch between the two peers
Why this is correct
Firmware upgrades can introduce new defaults that change the update message, causing checksum mismatch and flapping.
- ✗
The BGP hold timer has expired
Why it's wrong here
Hold timer expiry would result in the session going to Idle, not Active.
- ✗
The BGP neighbor is not reachable due to a routing issue
Why it's wrong here
If the neighbor were unreachable, the state would be Idle, not Active.
- ✗
The BGP password is incorrect
Why it's wrong here
An incorrect password would cause the session to stay in Idle state.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE7 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 NSE7 exam.