- A
The LDAP server certificate has expired.
Why wrong: A certificate issue would cause bind failure, but the administrator can bind successfully.
- B
The RADIUS server is not reachable.
Why wrong: RADIUS is not used in this scenario; the profile uses LDAP.
- C
The authentication sequence changed after upgrade.
Upgrades can rearrange authentication profiles or require re-selection, leading to authentication failures.
- D
The GP portal certificate is not trusted by the client.
Why wrong: Portal certificate trust issues cause client warnings, not authentication failures on the firewall.
Question 254 of 516
How an Altered Authentication Sequence Causes GlobalProtect Login Failure
This PCNSE practice question tests your understanding of troubleshoot. 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.
A company uses GlobalProtect for remote access. After upgrading the GP portal and gateway from 5.0 to 5.1, some users cannot connect. They report that they receive 'Unable to connect to gateway' error. The firewall logs show that the user is unable to authenticate. The authentication profile uses LDAP. The administrator can successfully bind to the LDAP server from the firewall CLI. What could be the issue?
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 authentication sequence changed after upgrade.
Option C is correct because after upgrading the GlobalProtect portal and gateway from version 5.0 to 5.1, the authentication sequence may have been reset or changed. If the authentication profile uses LDAP but the sequence now includes a RADIUS server that is unreachable or misconfigured, the user will fail to authenticate even though the LDAP bind works from the CLI. The error 'Unable to connect to gateway' combined with authentication failure points to a change in the authentication order, not a certificate or connectivity issue.
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 LDAP server certificate has expired.
Why it's wrong here
A certificate issue would cause bind failure, but the administrator can bind successfully.
- ✗
The RADIUS server is not reachable.
Why it's wrong here
RADIUS is not used in this scenario; the profile uses LDAP.
- ✓
The authentication sequence changed after upgrade.
Why this is correct
Upgrades can rearrange authentication profiles or require re-selection, leading to authentication failures.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The GP portal certificate is not trusted by the client.
Why it's wrong here
Portal certificate trust issues cause client warnings, not authentication failures on the firewall.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the LDAP bind success from the CLI confirms the entire authentication path works, but they overlook that the authentication sequence may have changed after the upgrade, causing the firewall to attempt a different method (like RADIUS) before falling back to LDAP.
Trap categories for this question
Scenario analysis trap
RADIUS is not used in this scenario; the profile uses LDAP.
Detailed technical explanation
How to think about this question
Under the hood, the GlobalProtect gateway authentication sequence is defined in the authentication profile and can include multiple authentication methods (e.g., LDAP, RADIUS, local database). After an upgrade, the sequence may be reordered or a previously disabled RADIUS server may become active, causing the gateway to attempt RADIUS authentication before LDAP. If the RADIUS server is unreachable or returns a reject, the user fails authentication even though LDAP is functional. This is a common issue when upgrading from 5.0 to 5.1 because the authentication profile configuration may be migrated with different defaults or the sequence order is not preserved.
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
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
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.
- →
Troubleshoot — study guide chapter
Learn the concepts, then practise the questions
- →
Troubleshoot 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?
Troubleshoot — This question tests Troubleshoot — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The authentication sequence changed after upgrade. — Option C is correct because after upgrading the GlobalProtect portal and gateway from version 5.0 to 5.1, the authentication sequence may have been reset or changed. If the authentication profile uses LDAP but the sequence now includes a RADIUS server that is unreachable or misconfigured, the user will fail to authenticate even though the LDAP bind works from the CLI. The error 'Unable to connect to gateway' combined with authentication failure points to a change in the authentication order, not a certificate or connectivity issue.
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 →
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.