CCNA Network Services and Security Practice Question
Network Topology
You are connected to R1. Configure PAT (NAT overload) so that hosts on the 192.168.1.0/24 LAN can access the Internet via the outside interface GigabitEthernet 0/1 with IP 203.0.113.2/29. The current configuration has an incorrect inside/outside interface assignment and a missing overload keyword. Fix all issues.
⚠ Common exam trap
A common trap is confusing which interface should be inside and which should be outside. Remember: inside is the private LAN side, outside is the public WAN side. Also, do not forget the 'overload' keyword for PAT, and ensure the ACL matches the correct source subnet.
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
✓
Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.
Three issues exist: (1) The inside and outside interfaces are swapped — GigabitEthernet0/0 (LAN) should be 'ip nat inside' and GigabitEthernet0/1 (WAN) should be 'ip nat outside'. (2) The PAT command lacks the 'overload' keyword. (3) ACL 10 permits 10.0.0.0/8 but the inside subnet is 192.168.1.0/24; ACL must be corrected. Fix with 'interface GigabitEthernet0/0', 'ip nat inside', 'interface GigabitEthernet0/1', 'ip nat outside', 'ip nat inside source list 10 interface GigabitEthernet0/1 overload', and 'access-list 10 permit 192.168.1.0 0.0.0.255'.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.
Why this is correct
This is correct because it fixes all three issues: the inside/outside interface assignments are swapped, the ACL permits the wrong subnet, and the PAT command lacks the 'overload' keyword. The correct configuration ensures proper NAT operation.
- ✗
Configure 'ip nat outside' on GigabitEthernet0/0, 'ip nat inside' on GigabitEthernet0/1, keep ACL 10 as is, and add 'overload' to the PAT command.
Why it's wrong here
This configuration marks the WAN side as inside and the LAN side as outside, so packets from the LAN are received on the 'outside' interface and are not matched by the 'ip nat inside source list' rule. Additionally, ACL 10 still permits the wrong subnet, so even if the interface roles were fixed, the NAT process would not select the intended internal addresses for translation. Adding 'overload' cannot compensate for the reversed inside/outside design and the faulty ACL.
- ✗
Configure 'ip nat inside' on GigabitEthernet0/1, 'ip nat outside' on GigabitEthernet0/0, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.
Why it's wrong here
With 'ip nat inside' assigned to GigabitEthernet0/1 (the WAN link) and 'ip nat outside' on the LAN interface, the router treats the public-facing connection as the internal side. Because the LAN is thus marked 'outside', traffic from 192.168.1.0/24 is never evaluated against the NAT ACL, even though ACL 10 now lists the correct subnet; the 'overload' keyword only enables port multiplexing on a correctly directed NAT rule. Consequently, internal hosts are not translated and the design fails.
- ✗
Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, but do not add 'overload' to the PAT command.
Why it's wrong here
Although the inside/outside markings and ACL 10 are correct, omitting 'overload' disables Port Address Translation. Without 'overload', the command attempts to translate inside local addresses to addresses from a configured global pool on a one-to-one basis; if the pool has only the single public IP on GigabitEthernet0/1, only one internal host can be translated at a time and the rest will fail. Adding 'overload' is mandatory for PAT-style many-to-one sharing of a single WAN address.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.Correct answer▾
Why this is correct
This is correct because it fixes all three issues: the inside/outside interface assignments are swapped, the ACL permits the wrong subnet, and the PAT command lacks the 'overload' keyword. The correct configuration ensures proper NAT operation.
✗Configure 'ip nat outside' on GigabitEthernet0/0, 'ip nat inside' on GigabitEthernet0/1, keep ACL 10 as is, and add 'overload' to the PAT command.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: The inside/outside interface assignment is reversed; ACL 10 permits 10.0.0.0/8 instead of 192.168.1.0/24.
Why candidates choose this
Candidates pick this because they might think the outside interface is the LAN side, or they overlook the ACL issue.
✗Configure 'ip nat inside' on GigabitEthernet0/1, 'ip nat outside' on GigabitEthernet0/0, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: The inside/outside interface assignment is reversed; the WAN interface should be outside, not inside.
Why candidates choose this
Candidates pick this because they might confuse which interface is inside and which is outside, or they think the 'inside' keyword refers to the internal network of the router.
✗Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, but do not add 'overload' to the PAT command.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: The 'overload' keyword is missing, which is required for PAT to enable many-to-one translation.
Why candidates choose this
Candidates pick this because they might think that NAT overload is enabled by default or that the 'overload' keyword is optional for PAT.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Go deeper
Related to this question
Learn chapter
Diagnosing DNS Record Issues — A, AAAA, CNAME, MX, NS, and PTR Records
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
Key term
ACL
An Access Control List is a set of rules that determines who or what can access specific network resources or data.
About these practice questions
One of 1,389 original 200-301 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco 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 200-301 exam.