PCNSE Core Concepts and Architecture Practice Question
A network security engineer is troubleshooting why a newly installed Palo Alto Networks firewall is not inspecting traffic between two internal subnets. The engineer confirms that the traffic is routed through the firewall, security policies are configured to allow and inspect the traffic, and no drop counters are incrementing. However, the firewall's session table shows sessions in an 'ACTIVE' state but with no application identified. Which component of the Palo Alto Networks Next-Generation Firewall is responsible for identifying the application in this scenario?
⚠ Common exam trap
Candidates often confuse App-ID with Content-ID, as both are 'ID' technologies, but only App-ID identifies the application.
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
✓
App-ID
App-ID is the Palo Alto Networks technology that identifies applications traversing the firewall. It uses signatures, protocol decoding, and behavioral heuristics to classify traffic accurately. In the scenario, sessions are active but no application is identified, indicating that App-ID has not yet completed its analysis. This could happen if the session is incomplete, if traffic is asymmetric, or if the application is unknown. Once App-ID identifies the application, the firewall can apply the appropriate security policy. The other options are related technologies but do not perform application identification.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
User-ID
Why it's wrong here
User-ID is the technology that maps IP addresses to users and groups, enabling policies based on user identity. It does not identify applications. In this scenario, the problem is application identification, not user mapping. User-ID would be relevant if policies were based on users and the mapping was failing, but the stem specifically mentions that no application is identified. Therefore, User-ID is not the component responsible for application identification.
- ✓
App-ID
Why this is correct
App-ID is the Palo Alto Networks traffic classification technology that identifies the application regardless of port, protocol, or evasion technique. In this scenario, sessions are active but no application is identified, meaning App-ID has not yet completed its classification. App-ID uses multiple identification mechanisms including application signatures, protocol decoding, and heuristics. Once App-ID identifies the application, it can enforce security policies based on the application. The lack of application identification could be due to incomplete session setup, asymmetric traffic, or insufficient packets for identification.
- ✗
Content-ID
Why it's wrong here
Content-ID is responsible for inspecting the content of allowed traffic for threats, URLs, and files. It operates after App-ID has identified the application and the security policy allows the session. In this scenario, the issue is that no application is identified, so Content-ID would not yet be engaged. Content-ID includes threat prevention, URL filtering, and file blocking. While Content-ID is critical for security, it is not the component that identifies the application itself.
- ✗
SSL Decryption
Why it's wrong here
SSL Decryption is a feature that decrypts SSL/TLS traffic to allow App-ID and Content-ID to inspect encrypted sessions. While it can enable application identification for encrypted traffic, it is not the component that performs the identification itself. In this scenario, the traffic might be unencrypted or the issue could be unrelated to encryption. The core component that identifies applications is App-ID, not SSL Decryption. SSL Decryption is an enabler, not the identifier.
Visual reference
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 |
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Palo Alto Networks exam blueprint
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.