The router between subnets is the most likely misconfigured device. This is correct because the client can successfully ping its own default gateway, which confirms that its local subnet connectivity and the gateway’s interface are functioning properly, yet it cannot reach a server on a different subnet. The core issue here is a routing problem: the router either lacks a route to the 10.0.0.0/24 network or is not correctly performing inter-subnet routing, causing it to drop packets destined for the server’s subnet. On the CompTIA ITF+ FC0-U61 exam, this scenario tests your understanding of how routers forward traffic between different subnets, and a common trap is to blame the client’s IP configuration or the server’s firewall when the client can already reach its gateway. Remember the memory tip: “If the gateway is pingable but the far subnet is unreachable, the router’s routing table is likely the problem.”
FC0-U61 Infrastructure Practice Question
This FC0-U61 practice question tests your understanding of infrastructure. 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.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 router must have a route to the server's subnet; without it, traffic cannot be forwarded.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The server's firewall
Why it's wrong here
A firewall could block traffic, but the ping failure is more likely due to lack of routing.
✗
The switch
Why it's wrong here
Switches forward frames based on MAC addresses and do not route between subnets.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
Under the hood, when the client sends a packet to 10.0.0.50, it compares the destination IP to its own subnet mask (/24) and determines the server is on a different network. The client then sends the packet to its default gateway (192.168.1.1) via ARP. The router must have a routing table entry for 10.0.0.0/24 pointing to the correct interface or next-hop; if missing, the router drops the packet and may send an ICMP Destination Unreachable (Network Unreachable) message. In real-world scenarios, this often occurs when a router lacks a static route or a dynamic routing protocol (e.g., OSPF) has not propagated the route.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this FC0-U61 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. PC1 (192.168.1.10) cannot communicate with PC2 (192.168.2.10). What is the most likely cause?
hard
A.PC2 has an incorrect default gateway
✓ B.Router1 lacks a route to the 192.168.2.0/24 network
C.Switch1 is not routing between VLANs
D.PC1 has an incorrect subnet mask
Why B: Router1 lacks a route to the 192.168.2.0/24 network, so when PC1 sends traffic to PC2, Router1 does not have a destination network entry in its routing table to forward the packets. Without a route, the router drops the packets and may send an ICMP Destination Unreachable message back to PC1. This is the most likely cause because PC1 can reach its default gateway (Router1), but Router1 cannot forward traffic to the remote subnet.
Variation 2. A technician is troubleshooting a workstation that cannot connect to a server at 192.168.1.100. The workstation's IP configuration shows: IP: 192.168.2.50, Subnet: 255.255.255.0, Gateway: 192.168.2.1. Which of the following is the MOST likely cause of the connectivity issue?
hard
A.Incorrect default gateway
B.Incorrect subnet mask
C.Duplicate IP address on the network
✓ D.Workstation and server are on different subnets with no routing
Why D: The workstation's IP address (192.168.2.50) and the server's IP address (192.168.1.100) belong to different subnets (192.168.2.0/24 and 192.168.1.0/24, respectively). Without a router configured to forward traffic between these subnets, the workstation cannot reach the server, even though the default gateway (192.168.2.1) is correct for its own subnet.
Variation 3. A technician is troubleshooting a network where users in one department cannot reach a web server in another subnet. The technician confirms the server is running and the switch ports are up. Which of the following should be checked NEXT?
hard
A.DHCP server scope
B.Firewall rules on the server
C.DNS server settings
✓ D.Router configuration
Why D: Since the server is running and switch ports are up, the issue is likely at Layer 3 (network layer). The router is responsible for forwarding traffic between subnets, so a misconfigured router (e.g., missing static route, incorrect ACL, or routing protocol issue) would prevent inter-subnet communication. Checking the router configuration is the logical next step to verify that routing is properly set up for the destination subnet.
Last reviewed: Jun 30, 2026
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