hardMultiple Choice
FC0-U71 Practice Question: A technician is troubleshooting a network issue…
A technician is troubleshooting a network issue where a client cannot reach a server on a different subnet. The client's IP is 192.168.1.10/24, and the server's IP is 10.0.0.50/24. The client can ping its default gateway. Which device is most likely misconfigured?
⚠ Common exam trap
CompTIA often tests the misconception that a client's inability to reach a different subnet is due to DNS or the server's firewall, but the key clue is that the client can ping its default gateway, isolating the problem to Layer 3 routing between subnets.
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 router between subnets
The client can ping its default gateway, indicating that its local subnet (192.168.1.0/24) connectivity and the gateway's interface are working. However, the client cannot reach a server on a different subnet (10.0.0.0/24). This points to a routing issue: the router between the subnets is likely misconfigured—either missing a route to the 10.0.0.0/24 network or not performing inter-VLAN routing correctly. Without proper routing, the router drops or fails to forward packets destined for the server's subnet.
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 client's DNS settings
Why it's wrong here
DNS resolves hostnames to IP addresses; the client already targets the server by IP, so name resolution plays no part in this reachability failure. DNS misconfiguration would be the culprit when pings to a hostname fail while pings to the same server's IP address succeed.
- ✓
The router between subnets
Why this is correct
The router between subnets must route traffic across the 192.168.1.0/24 and 10.0.0.0/24 boundaries, since the client's /24 mask confines it to its own subnet. The client reaching its gateway proves local connectivity works, so the fault lies in the router's routing configuration or interfaces, not the client or server.
- ✗
The server's firewall
Why it's wrong here
The client cannot even reach the server's subnet, so the failure occurs before any server-side packet filtering. A server firewall would be the likely cause if the client reached the host but specific ports or protocols were blocked while others succeeded.
- ✗
The switch
Why it's wrong here
A switch forwards frames within a subnet and does not perform the routing between 192.168.1.0/24 and 10.0.0.0/24, so it cannot cause this failure. Switches are the correct suspect when clients on the same VLAN lose connectivity or ports are misassigned.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This FC0-U71 practice question is part of Courseiva's free CompTIA 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 FC0-U71 exam.