- A
Certificate
Certificate authentication is supported for IPSec tunnels.
- B
RADIUS
Why wrong: RADIUS is used for user authentication, not for IPSec peer authentication.
- C
SAML
Why wrong: SAML is used for web-based authentication, not IPSec.
- D
LDAP
Why wrong: LDAP is used for user authentication, not IPSec.
- E
Pre-shared key
PSK is a standard IPSec authentication method.
Question 411 of 516
Supported IPsec Authentication Methods — Pre-Shared Key and Certificate | Palo Alto Networks Certified Network Security Explained
This PCNSE practice question tests your understanding of secure access and vpn. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO of the following are supported authentication methods for IPSec VPN tunnel setup between two Palo Alto Networks firewalls?
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
✓
Certificate
Palo Alto Networks firewalls support certificate-based authentication for IKEv1 and IKEv2 IPsec VPN tunnels, where each peer presents an X.509 certificate signed by a trusted CA. This method provides strong mutual authentication and is commonly used in large-scale or high-security deployments.
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.
- ✓
Certificate
Why this is correct
Certificate authentication is supported for IPSec tunnels.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
RADIUS
- ✗
SAML
Why it's wrong here
SAML is used for web-based authentication, not IPSec.
- ✗
LDAP
Why it's wrong here
LDAP is used for user authentication, not IPSec.
- ✓
Pre-shared key
Why this is correct
PSK is a standard IPSec authentication method.
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 confuse user authentication methods (RADIUS, SAML, LDAP) with device-to-device IPsec tunnel authentication, which only supports pre-shared keys and certificates on Palo Alto firewalls.
Detailed technical explanation
How to think about this question
IPsec tunnel authentication between two Palo Alto firewalls occurs during IKE phase 1, where each peer proves its identity using either a pre-shared key (PSK) or a digital certificate (X.509). PSK is simpler but less scalable, while certificate-based authentication leverages PKI for stronger security and supports features like certificate revocation lists (CRLs) and OCSP. Both methods are defined in RFC 2409 (IKEv1) and RFC 7296 (IKEv2).
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 junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
What to study next
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FAQ
Questions learners often ask
What does this PCNSE question test?
Secure Access and VPN — This question tests Secure Access and VPN — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Certificate — Palo Alto Networks firewalls support certificate-based authentication for IKEv1 and IKEv2 IPsec VPN tunnels, where each peer presents an X.509 certificate signed by a trusted CA. This method provides strong mutual authentication and is commonly used in large-scale or high-security deployments.
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.
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 →
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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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