CCNA Network Infrastructure and Connectivity Practice Question
Exhibit
! R1 running-config (partial)
hostname R1
!
interface GigabitEthernet0/0
ip address 203.0.113.1 255.255.255.252
no shutdown
!
interface GigabitEthernet0/1
ip address 192.168.1.1 255.255.255.0
no shutdown
!
ip route 0.0.0.0 0.0.0.0 203.0.113.2
!
! PC1 ipconfig output (from PC1)
Connection-specific DNS Suffix . : example.com
IPv4 Address. . . . . . . . . . . : 192.168.1.10
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1
DNS Servers . . . . . . . . . . . : 192.168.1.1
! Ping results from PC1:
ping 192.168.1.1 -> success
ping 203.0.113.1 -> success
ping 203.0.113.2 -> success
ping 8.8.8.8 -> Request timed out.
! show ip route on R1 (relevant lines)
S* 0.0.0.0/0 [1/0] via 203.0.113.2
192.168.1.0/24 is directly connected, GigabitEthernet0/1
203.0.113.0/30 is directly connected, GigabitEthernet0/0You are connected to R1 via the console. The network administrator reports that PC1 (connected to R1's GigabitEthernet0/1) cannot reach the internet. Troubleshoot the issue step by step. The current configuration and show outputs are provided.
⚠ Common exam trap
The trap is that candidates may focus on local misconfigurations (gateway, DNS, routing) when the evidence shows local connectivity works. Always verify step by step: if the client can ping the gateway and next hop, the problem is external.
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
✓
routing or NAT issue beyond the local network
The issue is that PC1 cannot reach the internet despite having correct IP, gateway, and DNS. PC1 can ping the default gateway and even the next-hop router (203.0.113.2), but fails to ping 8.8.8.8. This indicates that the problem is beyond the local network — likely a routing or NAT issue on the ISP side. However, the task requires troubleshooting client connectivity; the provided outputs show no misconfiguration on PC1 or R1. The fault is external (ISP not routing or no NAT), but the candidate must verify that client configuration is correct and then escalate or check the ISP link. For the PBQ, the candidate should confirm that PC1's IP, subnet mask, gateway, and DNS are correct, and that R1 has a default route and can reach the next hop. No configuration changes are needed on R1 or PC1; the problem is outside the scope of the local network.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
PC1 has an incorrect default gateway configured.
Why it's wrong here
A host's default gateway is the Layer 3 next-hop for all off-subnet traffic. The scenario states PC1 can successfully ping its default gateway, which verifies that the gateway IP is correctly configured and reachable at both Layer 2 and Layer 3. If the gateway were incorrect, the ping would either fail entirely or be sent to a different device, not produce the observed symptom. Thus, a misconfigured gateway cannot be the reason PC1 cannot reach 8.8.8.8.
- ✗
R1 is missing a default route to the ISP.
Why it's wrong here
For R1 to reach the ISP, it needs a route covering the ISP's next-hop address, such as 203.0.113.2. The scenario explicitly states that R1 can ping 203.0.113.2, meaning R1 has a valid route to that destination—either a default route or a more specific network route. Without any default route, forward traffic destined for the internet would have no next hop, but the successful ping to the ISP's router proves a path exists. Therefore, a missing default route is not the underlying cause of the connectivity failure to 8.8.8.8.
- ✓
routing or NAT issue beyond the local network
Why this is correct
Because PC1 can ping its local gateway and R1 can ping the ISP's next-hop router (203.0.113.2), all layers up to that boundary are proven operational. The failure point must therefore reside beyond the local network: within the ISP's routing domain, at a NAT boundary on the public interface, or due to upstream filtering. A routing or NAT misconfiguration here would permit traffic from PC1 to leave R1 but prevent the return path or forwarding to the public IP, exactly matching the observed symptom. This is the only option that aligns with a successful local and next-hop ping but a failed ping to 8.8.8.8.
- ✗
PC1 has a DNS resolution issue.
Why it's wrong here
DNS is only used to translate human-friendly hostnames into IP addresses; it does not participate in packet forwarding. The test pings 8.8.8.8, which is a literal IP address, so no DNS lookup is required for the ping to succeed. If DNS were misconfigured, pinging an IP address would still work, whereas pinging a hostname like google.com would fail. Since the failure occurs with a bare IP address, a DNS resolution problem is categorically irrelevant to this symptom.
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.
✓routing or NAT issue beyond the local networkCorrect answer▾
Why this is correct
Because PC1 can ping its local gateway and R1 can ping the ISP's next-hop router (203.0.113.2), all layers up to that boundary are proven operational. The failure point must therefore reside beyond the local network: within the ISP's routing domain, at a NAT boundary on the public interface, or due to upstream filtering. A routing or NAT misconfiguration here would permit traffic from PC1 to leave R1 but prevent the return path or forwarding to the public IP, exactly matching the observed symptom. This is the only option that aligns with a successful local and next-hop ping but a failed ping to 8.8.8.8.
✗PC1 has an incorrect default gateway configured.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that a reachable gateway implies correct configuration; if the gateway were wrong, pinging it would fail.
Why candidates choose this
Candidates often assume that internet connectivity issues are due to a misconfigured gateway, but the ability to ping the gateway rules this out.
✗R1 is missing a default route to the ISP.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that reachability to the next hop requires a route; if R1 were missing a default route, it could not forward packets to the next hop.
Why candidates choose this
Candidates often suspect missing default routes when internet access fails, but the ability to ping the next hop confirms routing is working.
✗PC1 has a DNS resolution issue.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that DNS is only needed for name resolution; pinging an IP address bypasses DNS entirely.
Why candidates choose this
Candidates often confuse internet connectivity issues with DNS problems, but the use of an IP address eliminates DNS as a factor.
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
Quick reference
IPv4 Address Class Summary
| Class | First Octet Range | Default Mask | Networks | Hosts per Network |
|---|---|---|---|---|
| A | 1–126 | /8 (255.0.0.0) | 126 | 16,777,214 |
| B | 128–191 | /16 (255.255.0.0) | 16,384 | 65,534 |
| C | 192–223 | /24 (255.255.255.0) | 2,097,152 | 254 |
| D | 224–239 | N/A | Multicast groups | — |
| E | 240–255 | N/A | Reserved / experimental | — |
127.x.x.x is reserved for loopback. Modern networks use CIDR (classless) rather than classful addressing.
Go deeper
Related to this question
Learn chapter
ICMP and Ping
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
Key term
NAT
NAT (Network Address Translation) is a method that allows multiple devices on a private network to share a single public IP address when accessing the internet.
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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.