- A
Check the NAT rule for correct interface assignment.
Why wrong: The NAT rule is already configured and internal access works, so NAT is likely functioning.
- B
Check the DNS proxy configuration on the firewall.
Why wrong: DNS proxy would affect name resolution, but the issue could persist even with DNS if the web traffic is blocked by policy.
- C
Review the security policy to ensure traffic from the internal zone to the external zone is allowed.
If internal access works but external website access fails, the most likely cause is a security policy blocking web traffic. Checking the security policy is the logical first step.
- D
Verify that the default route is active by checking the routing table.
Why wrong: Internal access working indicates routing is likely correct.
Troubleshooting Internet Access: Check Security Policy First
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 security administrator reports that they can ping and access internal resources, but cannot access any external websites. The firewall is configured with a default route pointing to the internet router, and the NAT policy includes a source NAT rule for the internal subnet. Which step should the administrator take first to troubleshoot this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
Review the security policy to ensure traffic from the internal zone to the external zone is allowed.
The administrator can ping and access internal resources but cannot reach external websites, which indicates that basic IP connectivity and internal routing are functional. Since the firewall has a default route and a source NAT rule configured, the most likely cause is that a security policy is blocking traffic from the internal zone to the external zone. In Palo Alto Networks firewalls, security policies are evaluated before NAT, so even with correct NAT and routing, traffic will be dropped if no allow rule exists for the session.
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.
- ✗
Check the NAT rule for correct interface assignment.
Why it's wrong here
The NAT rule is already configured and internal access works, so NAT is likely functioning.
- ✗
Check the DNS proxy configuration on the firewall.
Why it's wrong here
DNS proxy would affect name resolution, but the issue could persist even with DNS if the web traffic is blocked by policy.
- ✓
Review the security policy to ensure traffic from the internal zone to the external zone is allowed.
Why this is correct
If internal access works but external website access fails, the most likely cause is a security policy blocking web traffic. Checking the security policy is the logical first step.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Verify that the default route is active by checking the routing table.
Why it's wrong here
Internal access working indicates routing is likely correct.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to checking NAT or routing first because those are common misconfigurations, but the PCNSE exam emphasizes that security policy is the first gatekeeper in the firewall's processing order, and without an allow rule, no traffic passes regardless of NAT or route correctness.
Detailed technical explanation
How to think about this question
Palo Alto Networks firewalls use a three-step processing model: security policy lookup, then NAT (if applicable), then routing. Even if a source NAT rule exists for the internal subnet, the firewall will not translate or forward traffic unless a security policy explicitly allows the session from the internal zone to the external zone. A common real-world scenario is that a default allow rule is missing, or the interzone default rule is set to 'deny', which is the default behavior for new zones.
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.
Visual reference
What to study next
Got this wrong? Here's your next step.
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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: Review the security policy to ensure traffic from the internal zone to the external zone is allowed. — The administrator can ping and access internal resources but cannot reach external websites, which indicates that basic IP connectivity and internal routing are functional. Since the firewall has a default route and a source NAT rule configured, the most likely cause is that a security policy is blocking traffic from the internal zone to the external zone. In Palo Alto Networks firewalls, security policies are evaluated before NAT, so even with correct NAT and routing, traffic will be dropped if no allow rule exists for the session.
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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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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