- A
The App-ID signature for 'facebook-chat' is outdated.
Why wrong: Outdated signatures would cause misidentification, but the log shows correct app.
- B
The application 'facebook-chat' is a dependency that is not allowed in the policy.
Dependent apps must be allowed explicitly or using application group.
- C
The firewall is blocking the application 'facebook-chat' due to content filtering.
Why wrong: Blocking would show dropped sessions, not missing appID.
- D
The traffic is using a non-standard port for chat.
Why wrong: Facebook uses standard ports.
Question 128 of 516
Dependent Applications in App-ID — Allowing Sub-Applications like facebook-chat
This PCNSE practice question tests your understanding of securing traffic and app-id. 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.
A security policy has an application list with 'facebook-chat' and 'facebook-base'. A user reports that Facebook messages are being blocked. The firewall logs show the application as 'facebook-base' but not as 'facebook-chat'. What is the most likely reason?
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
✓
The application 'facebook-chat' is a dependency that is not allowed in the policy.
Option B is correct because 'facebook-chat' is a dependent application of 'facebook-base'. In Palo Alto Networks App-ID, dependent applications are sub-applications that are only identified when the parent application is detected. The logs show only 'facebook-base', indicating the traffic does not contain the specific characteristics to be identified as 'facebook-chat'. Although the policy explicitly lists both applications, the firewall identifies only one application per session. Since the traffic is matched to 'facebook-base', the 'facebook-chat' dependent application is not separately allowed, and the user's chat messages are blocked because they are not being recognized as the chat application.
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 App-ID signature for 'facebook-chat' is outdated.
Why it's wrong here
Outdated signatures would cause misidentification, but the log shows correct app.
- ✓
The application 'facebook-chat' is a dependency that is not allowed in the policy.
Why this is correct
Dependent apps must be allowed explicitly or using application group.
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.
- ✗
The firewall is blocking the application 'facebook-chat' due to content filtering.
Why it's wrong here
Blocking would show dropped sessions, not missing appID.
- ✗
The traffic is using a non-standard port for chat.
Why it's wrong here
Facebook uses standard ports.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume a missing application in logs means the signature is outdated or the traffic is on a non-standard port, rather than understanding that dependent applications require explicit policy allowance or that the parent application must be permitted first.
Trap categories for this question
Command / output trap
Outdated signatures would cause misidentification, but the log shows correct app.
Detailed technical explanation
How to think about this question
App-ID uses a multi-layered approach including protocol decoding, behavioral analysis, and signature matching to identify applications and their dependencies. For Facebook, 'facebook-base' is the parent application that handles the core HTTP/HTTPS traffic, while 'facebook-chat' is a dependent application that uses WebSocket or XMPP over the same session. If the security policy does not explicitly allow the dependent application, the firewall may still allow the parent application but block the dependent one, resulting in partial functionality like messages being blocked while other Facebook features work.
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.
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.
- →
Securing Traffic and App-ID — study guide chapter
Learn the concepts, then practise the questions
- →
Securing Traffic and App-ID practice questions
Targeted practice on this topic area only
- →
All PCNSE questions
516 questions across all exam domains
- →
Palo Alto Networks Certified Network Security Engineer PCNSE study guide
Full concept coverage aligned to exam objectives
- →
PCNSE practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related PCNSE practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Manage, Monitor and Operate practice questions
Practise PCNSE questions linked to Manage, Monitor and Operate.
Securing Traffic and App-ID practice questions
Practise PCNSE questions linked to Securing Traffic and App-ID.
Securing Users and Applications with Authentication practice questions
Practise PCNSE questions linked to Securing Users and Applications with Authentication.
Decryption and SSL Inspection practice questions
Practise PCNSE questions linked to Decryption and SSL Inspection.
Managing Troubleshooting and High Availability practice questions
Practise PCNSE questions linked to Managing Troubleshooting and High Availability.
Deploy and Configure Firewalls practice questions
Practise PCNSE questions linked to Deploy and Configure Firewalls.
Core Concepts and Architecture practice questions
Practise PCNSE questions linked to Core Concepts and Architecture.
Secure Access and VPN practice questions
Practise PCNSE questions linked to Secure Access and VPN.
Troubleshoot practice questions
Practise PCNSE questions linked to Troubleshoot.
PCNSE fundamentals practice questions
Practise PCNSE questions linked to PCNSE fundamentals.
PCNSE scenario practice questions
Practise PCNSE questions linked to PCNSE scenario.
PCNSE troubleshooting practice questions
Practise PCNSE questions linked to PCNSE troubleshooting.
Practice this exam
Start a free PCNSE practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this PCNSE question test?
Securing Traffic and App-ID — This question tests Securing Traffic and App-ID — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The application 'facebook-chat' is a dependency that is not allowed in the policy. — Option B is correct because 'facebook-chat' is a dependent application of 'facebook-base'. In Palo Alto Networks App-ID, dependent applications are sub-applications that are only identified when the parent application is detected. The logs show only 'facebook-base', indicating the traffic does not contain the specific characteristics to be identified as 'facebook-chat'. Although the policy explicitly lists both applications, the firewall identifies only one application per session. Since the traffic is matched to 'facebook-base', the 'facebook-chat' dependent application is not separately allowed, and the user's chat messages are blocked because they are not being recognized as the chat application.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More PCNSE practice questions
- Arrange the steps to enable and configure GlobalProtect on a Palo Alto Networks firewall.
- Order the steps to upgrade the PAN-OS software on a standalone firewall.
- An administrator notices that traffic from zone A to zone B is being dropped silently. Security rules are in place. Trou…
- Which component of the PAN-OS architecture is responsible for processing security policies and performing packet inspect…
- A company has configured a security policy that allows HTTP traffic from the internal network 10.0.0.0/8 to the internet…
- An organization wants to map user identity from Active Directory for traffic coming from internal LAN users without inst…
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.