CCNA Network Infrastructure and Connectivity Practice Question
Network Topology
You are connected to R1 via console. PC1 is connected to R1's GigabitEthernet0/1 interface and is configured with a static IP address. PC1 cannot reach the internet (203.0.113.1). Identify and resolve the connectivity issue. Configure R1 to restore full connectivity for PC1.
⚠ Common exam trap
The trap is that candidates may focus on routing (default route, routing protocols) or IP addressing (default gateway) when the real issue is NAT. Always verify if private IPs are being translated when hosts cannot reach the internet, even if the router itself has connectivity.
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 NAT overload on R1: define ACL 1 to permit 192.168.1.0 0.0.0.255, set GigabitEthernet0/0 as outside and GigabitEthernet0/1 as inside, and apply ip nat inside source list 1 interface GigabitEthernet0/0 overload.
PC1 has a default gateway of 192.168.1.1, which is correct, but R1 is not performing NAT. R1 can reach the internet (203.0.113.1) but PC1 cannot because R1 drops packets from PC1 destined to the internet without source NAT. The fix is to configure NAT overload (PAT) on R1: define an ACL to match PC1's subnet, configure the inside and outside interfaces, and enable NAT on the outside interface. This will translate PC1's private IP to R1's public IP.
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 NAT overload on R1: define ACL 1 to permit 192.168.1.0 0.0.0.255, set GigabitEthernet0/0 as outside and GigabitEthernet0/1 as inside, and apply ip nat inside source list 1 interface GigabitEthernet0/0 overload.
Why this is correct
This is correct because PC1 uses a private IP address (192.168.1.0/24) and needs NAT to reach the internet. The configuration defines the inside and outside interfaces, uses an ACL to match the private subnet, and enables PAT (overload) on the outside interface, translating PC1's source IP to R1's public IP.
- ✗
Configure a static route on R1: ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0 203.0.113.1.
Why it's wrong here
This is incorrect because R1 already has a default route (as indicated by the question's context that R1 can reach 203.0.113.1). The issue is not routing but NAT; PC1's packets are dropped because they have a private source IP and no translation is configured.
- ✗
Change PC1's default gateway to 203.0.113.1.
Why it's wrong here
This is incorrect because 203.0.113.1 is the internet IP, not on the same subnet as PC1 (192.168.1.0/24). PC1 cannot have a default gateway outside its own subnet; it must be on the same local network.
- ✗
Enable IP routing on R1 and configure OSPF.
Why it's wrong here
Enabling IP routing is unnecessary because R1 already routes packets between its directly connected subnets, and 'ip routing' is enabled by default on Cisco routers. OSPF is a dynamic routing protocol used to exchange routes with other routers, but it does nothing to translate PC1's private 192.168.1.x source address into the public 203.0.113.1 address that the internet requires for return traffic. The real failure is the absence of NAT overload, not a routing protocol or routing table issue, so OSPF would leave PC1 with an unroutable private source IP.
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 NAT overload on R1: define ACL 1 to permit 192.168.1.0 0.0.0.255, set GigabitEthernet0/0 as outside and GigabitEthernet0/1 as inside, and apply ip nat inside source list 1 interface GigabitEthernet0/0 overload.Correct answer▾
Why this is correct
This is correct because PC1 uses a private IP address (192.168.1.0/24) and needs NAT to reach the internet. The configuration defines the inside and outside interfaces, uses an ACL to match the private subnet, and enables PAT (overload) on the outside interface, translating PC1's source IP to R1's public IP.
✗Configure a static route on R1: ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0 203.0.113.1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that a default route is already in place and working; adding another does not solve the NAT problem.
Why candidates choose this
Candidates might think the issue is a missing default route, especially if they overlook that R1 can already ping the internet.
✗Change PC1's default gateway to 203.0.113.1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that a host's default gateway must be on the same subnet; 203.0.113.1 is not reachable directly from PC1.
Why candidates choose this
Candidates might mistakenly think the default gateway should be the internet router's IP, not understanding that the gateway must be local.
✗Enable IP routing on R1 and configure OSPF.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that OSPF does not solve the private-to-public address translation problem; it only exchanges routes between routers.
Why candidates choose this
Candidates might think that a routing protocol is needed to reach the internet, but in this scenario a static default route already exists.
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?”
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Related to this question
Learn chapter
IPv4 Addressing and Address Classes
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
Default gateway
A default gateway is a network device, typically a router, that acts as the exit point for traffic from a local network to other networks, including the internet.
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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.