NSE7 Troubleshooting and Diagnostics Practice Question
This NSE7 practice question tests your understanding of troubleshooting and diagnostics. 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 network administrator is troubleshooting an IPsec VPN tunnel that fails to establish. The remote gateway logs show a proposal mismatch. On FortiGate, the administrator runs 'diagnose vpn ike config' and sees 'proposal: aes128-sha1, aes256-sha256'. The remote side expects 'aes256-sha1'. 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Phase 1 proposal list does not include the algorithm combination the remote gateway requires
The proposal mismatch occurs because the FortiGate's IKE proposal includes aes256-sha256 but not aes256-sha1, and the remote gateway expects aes256-sha1. The correct action is to add aes256-sha1 to the proposal list.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 Phase 1 proposal list does not include the algorithm combination the remote gateway requires
Why this is correct
Correct. The local proposal list must contain at least one matching algorithm set that the remote gateway supports.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The pre-shared key is incorrect
Why it's wrong here
An incorrect pre-shared key would cause authentication failure, not proposal mismatch.
✗
The Phase 2 selectors are misconfigured
Why it's wrong here
Phase 2 selectors define which traffic is encrypted, not the encryption algorithm for IKE.
✗
The IKE version is set to 1 but remote uses 2
Why it's wrong here
The output shows IKE config, not version mismatch. A version mismatch would show different errors.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Command / output trap
The output shows IKE config, not version mismatch. A version mismatch would show different errors.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE7 NAT questions on configuration and troubleshooting.
Troubleshooting and Diagnostics — This question tests Troubleshooting and Diagnostics — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The Phase 1 proposal list does not include the algorithm combination the remote gateway requires — The proposal mismatch occurs because the FortiGate's IKE proposal includes aes256-sha256 but not aes256-sha1, and the remote gateway expects aes256-sha1. The correct action is to add aes256-sha1 to the proposal list.
What should I do if I get this NSE7 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related NSE7 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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