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PCNSA Practice Question: An administrator is configuring Network Address…

An administrator is configuring Network Address Translation (NAT) on a Palo Alto Networks firewall. Which of the following statements about the order of NAT rule evaluation is correct?

⚠ Common exam trap

The trap here is that candidates familiar with Cisco ASA or router NAT (which often uses order-independent or longest-match logic) assume the same applies to Palo Alto, but Palo Alto strictly uses top-down first-match evaluation for NAT rules, and NAT is processed before security rules.

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

NAT rules are evaluated from top to bottom, and the first match is applied

Palo Alto Networks firewalls evaluate NAT rules from top to bottom in the rulebase, applying the first matching rule to the traffic. This is analogous to security rule evaluation order, ensuring deterministic behavior for source and destination translation. Once a NAT rule matches, no further NAT rules are considered for that session.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • NAT rules are evaluated after security rules

    Why it's wrong here

    Security rules are evaluated first, then NAT rules are applied based on the translated packet.

  • NAT rules are evaluated from top to bottom, and the first match is applied

    Why this is correct

    NAT rules are ordered; the first rule that matches the traffic is used.

  • NAT rules use longest prefix match on the destination address

    Why it's wrong here

    NAT rule order is sequential, not longest match.

  • NAT rules cannot combine source and destination NAT in a single rule

    Why it's wrong here

    A single NAT rule can include both source and destination NAT (bidirectional).

Visual reference

Inside (Private) PC-A 10.0.0.1 PC-B 10.0.0.2 NAT Router Outside (Public) 203.0.113.1 Inside Global Server PAT: many private IPs share one public IP via unique port numbers

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This PCNSA 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 PCNSA exam.