The answer is to configure NAT overload on R1 by defining ACL 1 to permit 192.168.1.0 0.0.0.255, setting GigabitEthernet0/0 as outside and GigabitEthernet0/1 as inside, then applying ip nat inside source list 1 interface GigabitEthernet0/0 overload. This resolves the private IP internet access issue because R1 drops packets from PC1 destined to the internet without source translation; PC1’s default gateway is correct, but R1 lacks NAT overload to translate the private source to its own public IP. On the CCNA 200-301 v2 exam, this scenario tests your ability to troubleshoot NAT overload for private IP internet access, often hiding the fact that R1 itself can reach 203.0.113.1 while PC1 cannot—a common trap where candidates misdiagnose routing instead of missing NAT. Remember the three-step order: define the ACL for the inside network, mark inside and outside interfaces, then apply the overload command. A quick mnemonic is “ACL, Inside/Outside, Overload” to lock in the sequence.
CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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.
PC1 ipconfig output:
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : example.local
IPv4 Address. . . . . . . . . . . : 192.168.1.10
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1
R1# show ip interface brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 203.0.113.2 YES NVRAM up up
GigabitEthernet0/1 192.168.1.1 YES NVRAM up up
R1# show running-config | section interface GigabitEthernet0/1
interface GigabitEthernet0/1
ip address 192.168.1.1 255.255.255.0
no shutdown
R1# ping 203.0.113.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5)
PC1> ping 203.0.113.1
Pinging 203.0.113.1 with 32 bytes of data:
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Ping statistics for 203.0.113.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
A
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.
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.
B
Configure a static route on R1: ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0 203.0.113.1.
Why wrong: 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.
C
Change PC1's default gateway to 203.0.113.1.
Why wrong: 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.
D
Enable IP routing on R1 and configure OSPF.
Why wrong: This is incorrect because IP routing is already enabled (R1 can route between interfaces) and OSPF is a dynamic routing protocol, which is unnecessary here. The issue is NAT, not routing protocol configuration.
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.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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
This is incorrect because IP routing is already enabled (R1 can route between interfaces) and OSPF is a dynamic routing protocol, which is unnecessary here. The issue is NAT, not routing protocol configuration.
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?”
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 200-301 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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