The most likely cause is that the TCP echo probe is configured to use port 443, but the server at 8.8.8.8 does not support TCP echo on that port. A TCP echo probe, as defined by RFC 862, expects the destination server to echo back the exact data it receives, and this service is typically offered on port 7, not on port 443 which is reserved for HTTPS. Since 8.8.8.8 will not respond with a TCP echo on port 443, the probe fails, causing the SD-WAN performance SLA to show 'Status: dead' even though the interface is up and standard ping traffic succeeds. On the Fortinet NSE 7 Advanced Security exam, this scenario tests your understanding of how SD-WAN health checks differentiate between basic connectivity and application-specific probes; a common trap is assuming any open port will satisfy a TCP echo probe. Remember the memory tip: TCP echo lives on port 7, not 443—if you want HTTPS, use an HTTP-GET probe instead.
NSE7 Advanced Networking and SD-WAN Practice Question
This NSE7 practice question tests your understanding of advanced networking and sd-wan. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
During an SD-WAN health check, an administrator observes that a performance SLA for wan1 shows 'Status: dead' even though the interface is up and can ping the SLA server. The SLA configuration uses a TCP echo probe to 8.8.8.8 port 443. 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 probe protocol is TCP echo, but the server at 8.8.8.8 does not support TCP echo on port 443.
A TCP echo probe expects a TCP connection to the specified port, but the server must be configured to respond to TCP echo requests (RFC 862), which typically uses port 7. Using port 443 (HTTPS) would not result in a TCP echo response; the server would not send back the same data. The probe would fail, causing the SLA to show as dead.
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 performance SLA is configured with the wrong threshold.
Why it's wrong here
Thresholds affect status but not the probe failure itself.
✗
The firewall policy allowing the probe traffic is missing.
Why it's wrong here
If the interface is up and ping works, the policy likely allows traffic; the issue is the probe type.
✓
The probe protocol is TCP echo, but the server at 8.8.8.8 does not support TCP echo on port 443.
Why this is correct
TCP echo uses port 7 by default; using a different port will not elicit a proper echo response unless the server is configured for it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
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.
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 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 NSE7 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.
Advanced Networking and SD-WAN — This question tests Advanced Networking and SD-WAN — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The probe protocol is TCP echo, but the server at 8.8.8.8 does not support TCP echo on port 443. — A TCP echo probe expects a TCP connection to the specified port, but the server must be configured to respond to TCP echo requests (RFC 862), which typically uses port 7. Using port 443 (HTTPS) would not result in a TCP echo response; the server would not send back the same data. The probe would fail, causing the SLA to show as dead.
What should I do if I get this NSE7 question wrong?
Identify which NSE7 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.
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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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