CCNP Architecture Practice Question
A network engineer is planning a new branch office network. The branch will have a single Cisco IOS router that connects to the internet via a GigabitEthernet interface. The engineer wants to configure NAT to allow internal hosts to access the internet. Which NAT type should be configured to allow multiple internal hosts to share the single public IP address?
⚠ Common exam trap
It's easy for candidates to confuse dynamic NAT with PAT; dynamic NAT still requires a pool of public addresses and does not allow overloading a single address.
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
✓
Port Address Translation (PAT)
Port Address Translation (PAT), or NAT overload, is designed to allow many internal hosts to share a single public IP address. It uses unique source port numbers to distinguish between sessions, making it the most efficient use of a single public IP. This is the standard method for branch offices with a single internet connection.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Static NAT
Why it's wrong here
Static NAT creates a one-to-one mapping between a private IP address and a public IP address. It does not allow multiple internal hosts to share a single public IP. Static NAT is typically used for servers that need to be accessible from the internet, not for outbound internet access for multiple hosts.
- ✗
Dynamic NAT
Why it's wrong here
Dynamic NAT maps private IP addresses to a pool of public IP addresses on a first-come, first-served basis. It still requires a pool of public IPs; if the pool is exhausted, additional hosts cannot access the internet. It does not allow multiple hosts to share a single public IP simultaneously, unlike PAT.
- ✗
NAT64
Why it's wrong here
NAT64 is used to translate between IPv6 and IPv4 addresses, allowing IPv6-only hosts to communicate with IPv4 servers. It is not used for sharing a single public IPv4 address among multiple IPv4 internal hosts. The scenario involves IPv4 internal hosts accessing the IPv4 internet, so NAT64 is irrelevant.
- ✓
Port Address Translation (PAT)
Why this is correct
PAT, also known as NAT overload, allows multiple internal hosts to share a single public IP address by translating both IP addresses and port numbers. Each internal host's connections are tracked using unique source port numbers, enabling thousands of simultaneous connections through one public IP. This is the correct choice for the scenario.
Visual reference
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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