CCNA Network Infrastructure and Connectivity Practice Question
A network administrator receives a call from a user who cannot access any external websites from their wired workstation. The user can ping the default gateway successfully, but fails to ping 8.8.8.8. The administrator runs ipconfig /all on the workstation and sees an IP address of 192.168.1.50, subnet mask 255.255.255.0, and default gateway 192.168.1.1. What is the most likely cause of this issue?
⚠ Common exam trap
This question tests the ability to differentiate between local connectivity issues and routing issues. A common trap is to assume DNS is the problem when users cannot access websites, but the failure to ping an external IP indicates a routing problem, not a name resolution problem. Also, successful ping to the gateway eliminates many Layer 2 or IP configuration issues.
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
✓
The workstation has an incorrect default gateway configured.
The user can successfully ping 192.168.1.1, proving local IP connectivity to that device. However, the device at 192.168.1.1 may not be the correct default gateway for reaching external networks; the actual gateway router might be at a different IP (e.g., 192.168.1.254). This misconfiguration explains why pings to 8.8.8.8 fail even though the local gateway responds, as the workstation sends external traffic to the wrong next-hop address.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The workstation has an incorrect default gateway configured.
Why this is correct
The user can ping the default gateway (192.168.1.1) but cannot ping 8.8.8.8, indicating local connectivity works but external routing fails. If the actual network gateway is different (e.g., 192.168.1.254), the workstation's configured gateway would be incorrect, preventing traffic from being forwarded to external networks.
- ✗
The workstation has a duplicate IP address on the network.
Why it's wrong here
A duplicate IP address would produce ARP address-conflict events and cause intermittent or unstable gateway reachability, because other hosts' ARP caches would flip between MAC addresses for the same IP. The workstation here consistently and successfully pinged 192.168.1.1, which is strong evidence that its own source IP is unique and not in an ARP conflict. Even a sporadic duplicate could still disrupt the ping to 8.8.8.8, but the reliable local connectivity to the default gateway rules out IP duplication as the root cause.
- ✗
The workstation is connected to the wrong VLAN.
Why it's wrong here
Being on the wrong VLAN would likely prevent the workstation from reaching the default gateway entirely, as the gateway is typically on the same VLAN. Since the user can ping the gateway, the VLAN assignment is likely correct.
- ✗
The workstation has a DNS misconfiguration.
Why it's wrong here
DNS misconfiguration only breaks name resolution, translating human-friendly hostnames into IP addresses. The failed ping to 8.8.8.8 is a direct ICMP echo request to a numeric IPv4 address, so the workstation never performs a DNS lookup. Even if the DNS servers were completely wrong, a user can always ping a public IP directly; the problem here is at Layer 3 routing, not at the application or name-resolution layer.
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.
✓The workstation has an incorrect default gateway configured.Correct answer▾
Why this is correct
The user can ping the default gateway (192.168.1.1) but cannot ping 8.8.8.8, indicating local connectivity works but external routing fails. If the actual network gateway is different (e.g., 192.168.1.254), the workstation's configured gateway would be incorrect, preventing traffic from being forwarded to external networks.
✗The workstation has a duplicate IP address on the network.Wrong answer — click to see why▾
Why this is wrong here
A duplicate IP would typically cause address conflict messages and prevent reliable communication with the gateway, but the user can ping the gateway successfully.
Why candidates choose this
Candidates may think duplicate IP causes general connectivity issues, but local connectivity would also be affected.
✗The workstation is connected to the wrong VLAN.Wrong answer — click to see why▾
Why this is wrong here
Wrong VLAN would usually result in no connectivity to the gateway, but here the gateway is reachable.
Why candidates choose this
Candidates may confuse VLAN misconfiguration with routing issues, but local connectivity to the gateway indicates correct VLAN membership.
✗The workstation has a DNS misconfiguration.Wrong answer — click to see why▾
Why this is wrong here
DNS is used to resolve hostnames to IP addresses; pinging an IP address bypasses DNS entirely.
Why candidates choose this
Candidates often associate web access issues with DNS, but the problem here is with IP connectivity, not name resolution.
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
IPv4 Addressing and Address Classes
Key term
IP address
An IP address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.
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.
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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.