This PCNSA practice question tests your understanding of decryption and monitoring. 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.
An admin notices that decryption is failing for some sites with error 'SSL Handshake Failed' in the traffic log. The decryption policy uses a custom SSL/TLS service profile with 'Allow Self-Signed Certificates' enabled. The firewall's certificate was issued by an internal CA. What should the admin check first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The server certificate chain is invalid
Option C is correct because the error 'SSL Handshake Failed' typically indicates a problem with the server certificate chain, such as an intermediate CA certificate missing or an untrusted root. Even with 'Allow Self-Signed Certificates' enabled, the firewall must validate the entire certificate chain for forward decryption; if the chain is invalid or incomplete, the handshake fails. The admin should first verify that the server's certificate chain is complete and trusted by the firewall's certificate store.
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 firewall's certificate is expired
Why it's wrong here
An expired firewall certificate would affect all decrypted sessions, not just specific sites.
✗
The decryption policy's action is set to 'decrypt'
Why it's wrong here
The policy action must be 'decrypt' for decryption to occur; this is correctly configured.
✓
The server certificate chain is invalid
Why this is correct
An invalid or incomplete server certificate chain is a common cause of SSL handshake failure.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The client is using an outdated browser
Why it's wrong here
Outdated browser may cause client-side issues but not an SSL handshake failure at the firewall level.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume enabling 'Allow Self-Signed Certificates' bypasses all certificate validation, but in reality, the firewall still validates the full certificate chain, and a broken chain causes the handshake to fail.
Detailed technical explanation
How to think about this question
During SSL/TLS forward proxy decryption, the firewall terminates the client connection and initiates a new SSL/TLS handshake with the server. The firewall must validate the server's certificate chain against its own trust store; if any certificate in the chain is self-signed, expired, or missing an intermediate CA, the handshake fails with 'SSL Handshake Failed'. The 'Allow Self-Signed Certificates' option only applies to the server certificate itself, not the entire chain—if an intermediate CA is invalid, the handshake still fails.
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.
TExam Day Tips
→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 PCNSA 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Decryption and Monitoring — This question tests Decryption and Monitoring — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The server certificate chain is invalid — Option C is correct because the error 'SSL Handshake Failed' typically indicates a problem with the server certificate chain, such as an intermediate CA certificate missing or an untrusted root. Even with 'Allow Self-Signed Certificates' enabled, the firewall must validate the entire certificate chain for forward decryption; if the chain is invalid or incomplete, the handshake fails. The admin should first verify that the server's certificate chain is complete and trusted by the firewall's certificate store.
What should I do if I get this PCNSA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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