- A
DNS resolution failure
Why wrong: DNS failure would prevent initial connection, not cause intermittent timeouts with active sessions.
- B
Asymmetric routing
Asymmetric routing causes the firewall to see packets that don't match existing sessions, leading to drops or session re-creation.
- C
Security policy configured with service 'any'
Why wrong: Using 'any' service is permissive and would not cause intermittent drops.
- D
Incomplete TCP three-way handshake
Why wrong: Incomplete handshake would prevent session creation, but sessions already exist.
Question 110 of 516
Intermittent Connectivity: Asymmetric Routing and Session Timeouts
This PCNSE practice question tests your understanding of troubleshoot. 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 user reports intermittent connectivity to a database server through the firewall. The session table shows active sessions, but the user experiences timeouts. 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 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
✓
Asymmetric routing
The correct answer is B because asymmetric routing causes the firewall to see only one direction of a TCP session, leading to session timeouts despite active session entries. When traffic from the client to the database server traverses one firewall and return traffic takes a different path, the firewall cannot properly track the TCP state, resulting in dropped packets and intermittent connectivity.
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.
- ✗
DNS resolution failure
Why it's wrong here
DNS failure would prevent initial connection, not cause intermittent timeouts with active sessions.
- ✓
Asymmetric routing
Why this is correct
Asymmetric routing causes the firewall to see packets that don't match existing sessions, leading to drops or session re-creation.
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.
- ✗
Security policy configured with service 'any'
Why it's wrong here
Using 'any' service is permissive and would not cause intermittent drops.
- ✗
Incomplete TCP three-way handshake
Why it's wrong here
Incomplete handshake would prevent session creation, but sessions already exist.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see 'active sessions' in the table and assume the firewall is working correctly, overlooking that asymmetric routing can leave stale entries while actual data flow is disrupted.
Detailed technical explanation
How to think about this question
Asymmetric routing breaks stateful inspection because the firewall relies on the session table to match return traffic to the original flow; if return packets arrive on a different interface or firewall, they are treated as unsolicited and dropped. This is common in multi-homed networks or when using policy-based routing (PBR) that does not account for firewall state. The firewall's session timeout settings (e.g., TCP default of 3600 seconds) may keep the session entry alive, but the missing return traffic causes the client to retransmit and eventually time out.
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 PCNSE 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.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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.
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Troubleshoot — study guide chapter
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FAQ
Questions learners often ask
What does this PCNSE question test?
Troubleshoot — This question tests Troubleshoot — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Asymmetric routing — The correct answer is B because asymmetric routing causes the firewall to see only one direction of a TCP session, leading to session timeouts despite active session entries. When traffic from the client to the database server traverses one firewall and return traffic takes a different path, the firewall cannot properly track the TCP state, resulting in dropped packets and intermittent connectivity.
What should I do if I get this PCNSE 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: "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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Last reviewed: Jul 4, 2026
This PCNSE practice question is part of Courseiva's free Palo Alto Networks 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 PCNSE exam.
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