The answer is to define a custom application object with the correct protocol signature and protocol type. This is correct because the firewall’s default SSL application identification relies on port-based heuristics, so traffic over TCP 44321—a port within the default SSL range—is misidentified regardless of the actual payload. By creating a custom application object that specifies a unique protocol signature (such as a pattern match or protocol decoder) and explicitly sets the protocol type to TCP, you override the port-based definition and force the firewall to inspect the traffic’s actual characteristics. On the PCNSE exam, this scenario tests your understanding of the difference between application override and custom application definition; a common trap is assuming an override rule is needed when the real solution is a properly defined custom object with a signature. Memory tip: “Override is for bypassing, definition is for identifying—if the traffic is truly a custom app, define it with a signature, don’t just override the port.”
PCNSE Core Concepts and Architecture Practice Question
This PCNSE practice question tests your understanding of core concepts and architecture. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Exhibit
Refer to the exhibit.
```
admin@PA-3020> show session info
session id 12345, application: ssl, vsys vsys1, zone trust->untrust
source 10.1.1.10:443 -> destination 192.168.1.1:44321
state: active, type: dynamic
session age: 120 sec, timeout: 3600 sec
admin@PA-3020> show system info | match uptime
Uptime: 30 days, 4 hours, 12 minutes
```
An administrator runs the commands and sees the output. The session shows an SSL application from trust to untrust. However, the traffic is actually a custom application over TCP 44321 that the firewall incorrectly identifies as SSL. Which configuration step will most accurately identify the custom application?
Refer to the exhibit.
```
admin@PA-3020> show session info
session id 12345, application: ssl, vsys vsys1, zone trust->untrust
source 10.1.1.10:443 -> destination 192.168.1.1:44321
state: active, type: dynamic
session age: 120 sec, timeout: 3600 sec
admin@PA-3020> show system info | match uptime
Uptime: 30 days, 4 hours, 12 minutes
```
A
Disable SSL inspection on the security policy for this traffic.
Why wrong: Disabling inspection may cause the firewall to not identify the application at all.
B
Create an application override policy for this traffic to mark it as the custom application.
Why wrong: Application override forces the application but does not help the firewall learn the actual protocol; it bypasses App-ID.
C
Enable SSL decryption on the traffic to inspect the payload.
Why wrong: Decryption only works if the traffic is actually SSL; the custom app is misidentified as SSL.
D
Define a custom application object with the correct protocol signature and protocol type.
A custom application object allows the firewall to accurately identify the traffic based on its actual protocol characteristics.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Define a custom application object with the correct protocol signature and protocol type.
Option D is correct because the firewall is misidentifying the custom application as SSL due to the use of TCP port 44321, which falls within the default SSL port range. By defining a custom application object with the correct protocol signature (e.g., a protocol decoder or pattern match) and specifying the protocol type (e.g., TCP), the firewall can accurately classify the traffic based on actual payload characteristics rather than relying on port-based heuristics.
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.
✗
Disable SSL inspection on the security policy for this traffic.
Why it's wrong here
Disabling inspection may cause the firewall to not identify the application at all.
✗
Create an application override policy for this traffic to mark it as the custom application.
Why it's wrong here
Application override forces the application but does not help the firewall learn the actual protocol; it bypasses App-ID.
✗
Enable SSL decryption on the traffic to inspect the payload.
Why it's wrong here
Decryption only works if the traffic is actually SSL; the custom app is misidentified as SSL.
✓
Define a custom application object with the correct protocol signature and protocol type.
Why this is correct
A custom application object allows the firewall to accurately identify the traffic based on its actual protocol characteristics.
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 often confuse application override (which forces classification) with custom application definition (which teaches the firewall to correctly identify the traffic), leading them to choose Option B instead of D.
Detailed technical explanation
How to think about this question
The firewall's Application and Threat Prevention (ATP) engine uses protocol decoders and application signatures to identify traffic. By default, SSL is identified via port heuristics (e.g., TCP 443, 44321) and handshake patterns. Creating a custom application object allows you to define a unique signature (e.g., a byte pattern at a specific offset) and associate it with the correct protocol type, overriding the default port-based detection. In a real-world scenario, this is critical for custom protocols like proprietary database replication or IoT device communication that use non-standard ports.
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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Core Concepts and Architecture — This question tests Core Concepts and Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Define a custom application object with the correct protocol signature and protocol type. — Option D is correct because the firewall is misidentifying the custom application as SSL due to the use of TCP port 44321, which falls within the default SSL port range. By defining a custom application object with the correct protocol signature (e.g., a protocol decoder or pattern match) and specifying the protocol type (e.g., TCP), the firewall can accurately classify the traffic based on actual payload characteristics rather than relying on port-based heuristics.
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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Question Discussion
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