CCNP Infrastructure Practice Question
A network engineer is configuring a Cisco IOS router for NAT overload (PAT) to allow internal hosts on the 10.1.1.0/24 network to access the internet using the router's outside interface IP address. The engineer wants to ensure that all internal hosts can initiate connections and that return traffic is correctly translated. Which configuration is required?
⚠ Common exam trap
Test-takers frequently confuse NAT overload using an interface with NAT using a pool, or misusing the outside source command, which is for different translation scenarios.
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
✓
ip nat inside source list 1 interface GigabitEthernet0/0 overload, with an access list permitting 10.1.1.0/24, and interfaces marked as inside and outside.
The correct configuration uses ip nat inside source list with the interface keyword and overload to translate internal addresses to the outside interface IP. This enables PAT, allowing multiple internal hosts to share the single public IP. The access list must permit the internal subnet, and interfaces must be correctly marked as inside and outside for NAT to operate.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ip nat inside source list 1 interface GigabitEthernet0/0 overload, with an access list permitting 10.1.1.0/24, and interfaces marked as inside and outside.
Why this is correct
This configuration enables NAT overload (PAT) by translating all internal addresses matching the access list to the outside interface's IP address. The overload keyword allows multiple hosts to share the same public IP. Marking interfaces as inside and outside is essential for NAT to function correctly. This meets the requirements.
- ✗
ip nat inside source static 10.1.1.1 203.0.113.1, with interfaces marked as inside and outside.
Why it's wrong here
This command creates a static NAT translation for a single internal address to a single public address. It does not provide PAT for multiple hosts and does not use the outside interface IP address. It would only allow one host to be translated, not the entire subnet.
- ✗
ip nat inside source list 1 pool MYPOOL overload, with a pool of public addresses, and interfaces marked as inside and outside.
Why it's wrong here
This configuration uses a pool of public addresses for NAT overload. While it would work, the scenario specifies using the router's outside interface IP address, not a pool. Using a pool would require additional public IPs and is not necessary. The correct configuration should use the interface keyword.
- ✗
ip nat outside source list 1 interface GigabitEthernet0/0 overload, with an access list permitting 10.1.1.0/24, and interfaces marked as inside and outside.
Why it's wrong here
The command ip nat outside source is used for translating outside source addresses, typically for reverse NAT or overlapping networks. It is not used for translating internal addresses to an outside interface. Using outside source would not achieve the desired PAT for internal hosts accessing the internet.
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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