- A
Use HA3 link for session synchronization
Why wrong: HA3 is for packet forwarding, not session sync.
- B
Enable asymmetric routing support
Why wrong: Asymmetric routing support helps with routing, not FTP session continuity.
- C
Enable UDP session synchronization
Why wrong: FTP uses TCP, not UDP.
- D
Configure an application layer gateway (ALG) for FTP
ALG ensures FTP control and data sessions remain intact.
Question 364 of 516
Preserve FTP Sessions During HA Failover with Application Layer Gateway
This PCNSE practice question tests your understanding of managing troubleshooting and high availability. 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.
In an HA active/passive setup, the engineer wants to ensure that during a failover, existing FTP data sessions are not interrupted. What additional configuration is required beyond default session synchronization?
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
✓
Configure an application layer gateway (ALG) for FTP
FTP uses separate control and data channels, and the data channel port is dynamically negotiated via the PORT or PASV command. Without an application layer gateway (ALG) for FTP, the firewall cannot track these dynamic ports, so session synchronization would only replicate the control session, causing data sessions to drop after a failover. Enabling the FTP ALG ensures the firewall inspects FTP commands and creates the necessary pinholes for data sessions, which are then synchronized to the passive peer.
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.
- ✗
Use HA3 link for session synchronization
Why it's wrong here
HA3 is for packet forwarding, not session sync.
- ✗
Enable asymmetric routing support
Why it's wrong here
Asymmetric routing support helps with routing, not FTP session continuity.
- ✗
Enable UDP session synchronization
- ✓
Configure an application layer gateway (ALG) for FTP
Why this is correct
ALG ensures FTP control and data sessions remain intact.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume session synchronization alone is sufficient for all TCP sessions, overlooking that FTP's dynamic port negotiation requires application-layer inspection to create and sync the data channel sessions.
Detailed technical explanation
How to think about this question
FTP ALG works by inspecting FTP control channel commands (PORT, PASV, EPSV) to extract the IP address and port for the data channel, then dynamically creating and synchronizing the corresponding data session entries. In an HA active/passive setup, the passive firewall must have these data session entries pre-populated via session synchronization; without the ALG, the passive firewall has no record of the data channel and will drop the TCP SYN for the data connection after failover. This is especially critical for active FTP (PORT mode), where the client initiates the data connection to a server-specified port, as the firewall must allow inbound traffic on that ephemeral port.
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.
Visual reference
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
What to study next
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FAQ
Questions learners often ask
What does this PCNSE question test?
Managing Troubleshooting and High Availability — This question tests Managing Troubleshooting and High Availability — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure an application layer gateway (ALG) for FTP — FTP uses separate control and data channels, and the data channel port is dynamically negotiated via the PORT or PASV command. Without an application layer gateway (ALG) for FTP, the firewall cannot track these dynamic ports, so session synchronization would only replicate the control session, causing data sessions to drop after a failover. Enabling the FTP ALG ensures the firewall inspects FTP commands and creates the necessary pinholes for data sessions, which are then synchronized to the passive peer.
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.
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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