The correct answer is that the DNS server is not reachable. When a user can communicate with other devices on the local network but cannot access the internet, the issue is typically with either the default gateway or DNS resolution; since local traffic works via IP addresses, a missing or unreachable DNS server prevents the system from translating domain names into IP addresses, blocking all internet access while leaving local connectivity intact. On the CompTIA ITF+ FC0-U61 exam, this scenario tests your understanding of the OSI model’s application and network layers, specifically how DNS operates separately from routing—a common trap is confusing a gateway failure (which would block all external traffic) with a DNS failure (which only blocks name resolution). To remember this, think of DNS as the phonebook: you can dial a local number (IP) directly, but without the phonebook, you cannot look up any new contacts (websites) to call.
FC0-U61 IT Concepts and Terminology Practice Question
This FC0-U61 practice question tests your understanding of it concepts and terminology. 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 user reports being unable to access the internet, but can reach other devices on the local network. Based on the exhibit, what is the most likely cause?
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 DNS server is not reachable.
Since the user can reach other devices on the local network but cannot access the internet, the issue is likely with the default gateway or DNS resolution. Option D is correct because if the DNS server is unreachable, the user can still communicate with local devices via IP addresses but cannot resolve domain names to access internet resources. The exhibit likely shows a valid IP address and subnet mask, but the DNS server address is missing or incorrect, preventing name resolution.
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 DNS server 8.8.8.8 might be blocked or unreachable.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume internet access failure is always a gateway problem, but the ability to reach local devices isolates the issue to DNS or gateway; the exhibit likely shows a valid gateway IP, making DNS the correct answer.
Detailed technical explanation
How to think about this question
DNS resolution uses UDP port 53 by default, and if the DNS server is unreachable (e.g., due to a firewall blocking outbound DNS queries or an incorrect DNS server address), the client will fail to resolve domain names like google.com, even though IP-based communication (e.g., pinging 8.8.8.8) might still work. In Windows, the `nslookup` command can test DNS resolution directly, while `ipconfig /all` shows the configured DNS server. A common real-world scenario is when a user can ping an external IP but cannot browse the web, pointing to a DNS issue rather than a routing problem.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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.
IT Concepts and Terminology — This question tests IT Concepts and Terminology — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The DNS server is not reachable. — Since the user can reach other devices on the local network but cannot access the internet, the issue is likely with the default gateway or DNS resolution. Option D is correct because if the DNS server is unreachable, the user can still communicate with local devices via IP addresses but cannot resolve domain names to access internet resources. The exhibit likely shows a valid IP address and subnet mask, but the DNS server address is missing or incorrect, preventing name resolution.
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. A user is unable to access the internet but can ping the default gateway. Based on the exhibit, what is the most likely cause?
hard
A.Firewall blocking traffic
B.Duplicate IP address
✓ C.Incorrect DNS server
D.Incorrect subnet mask
Why C: The user can ping the default gateway, which confirms that Layer 3 connectivity to the local network is working and that the firewall is not blocking ICMP traffic. However, the inability to access the internet (by name or IP) while local connectivity works points to a failure in name resolution. An incorrect DNS server address prevents the client from resolving domain names to IP addresses, which is the most likely cause given the symptoms.
Variation 2. A technician is troubleshooting a user's inability to access the internet. The user can ping the default gateway but cannot ping external websites. What is the most likely issue?
medium
A.Firewall is blocking all outbound traffic
B.Default gateway is down
C.IP address is misconfigured
✓ D.DNS server is not configured or is unreachable
Why D: The user can ping the default gateway, which confirms that the local network configuration (IP address, subnet mask, and gateway) is correct and that Layer 3 connectivity to the router is working. However, pinging external websites fails because the DNS server is not configured or unreachable, preventing the resolution of domain names to IP addresses. This is a classic symptom: internal connectivity works, but name resolution fails.
Last reviewed: Jun 11, 2026
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This FC0-U61 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-U61 exam.
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