PCNSE Deploy and Configure Firewalls Practice Question
A company needs to provide internet access to 500 internal users using a single public IP address. Which NAT method should be configured?
⚠ Common exam trap
It's easy for candidates to confuse Dynamic NAT (which still requires a pool of public IPs) with PAT, assuming any 'dynamic' method can share a single IP, but only PAT performs port-level multiplexing to achieve this.
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
✓
Source NAT with IP and port translation (PAT)
Source NAT with IP and port translation (PAT) allows 500 internal users to share a single public IP address by translating each private source IP:port combination to the public IP with a unique source port. This conserves public IPv4 addresses and is the standard method for large-scale internet access from a private network.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Dynamic NAT (1:1 pool)
Why it's wrong here
A dynamic NAT pool requires at least as many public addresses as concurrent translations, so one public IP cannot translate 500 internal hosts. It is tempting because dynamic NAT suits outbound internet access for a small group of internal users when a pool of public addresses is available.
- ✗
Static NAT (1:1)
Why it's wrong here
Static NAT maps one private address to one public address permanently, so a single public IP cannot serve 500 users concurrently. It is tempting because static NAT suits inbound publishing of a fixed internal server, such as a mail or web host reachable from the internet, where a stable one-to-one mapping is genuinely required.
- ✗
Destination NAT
Why it's wrong here
Destination NAT rewrites the destination address of inbound connections, typically to publish an internal server, so it cannot translate 500 outbound source addresses onto one public IP. It is tempting because destination NAT is the right choice when external users must reach an internal service behind a single public address.
- ✓
Source NAT with IP and port translation (PAT)
Why this is correct
Source NAT with port translation multiplexes 500 internal sessions onto one public address by rewriting source ports, so each flow is uniquely identified in the translation table. This satisfies the stem's single-public-IP constraint, which static or dynamic IP-only NAT cannot, since those require one public address per internal host.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.