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 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?
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.
Firewall is blocking all outbound traffic
Why wrong: A firewall blocking all outbound would also block ping to the gateway.
Default gateway is down
Why wrong: The gateway is reachable, so it is not down.
IP address is misconfigured
Why wrong: If the gateway is pingable, the IP configuration is likely correct.
DNS server is not configured or is unreachable
Pinging external sites by name fails if DNS is not resolving.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
DNS server is not configured or is unreachable
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Firewall is blocking all outbound traffic
Default gateway is down
Why it's wrong here
The gateway is reachable, so it is not down.
IP address is misconfigured
Why it's wrong here
If the gateway is pingable, the IP configuration is likely correct.
DNS server is not configured or is unreachable
Why this is correct
Pinging external sites by name fails if DNS is not resolving.
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
The trap here is that candidates often assume a firewall is blocking traffic (Option A) when they see internet failure, but the ability to ping the gateway proves Layer 3 connectivity is intact, pointing instead to a DNS resolution issue.
Detailed technical explanation
When a user pings an external website by name (e.g., www.example.com), the system first performs a DNS query to resolve the name to an IP address. If the DNS server is unreachable or misconfigured, the query fails with a 'Name or service not known' error, while ICMP echo requests to the gateway succeed. In real-world scenarios, this often occurs when the DNS server address is manually set to an incorrect IP or when the DHCP server fails to provide a valid DNS server.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
IT Concepts and Terminology — This question tests IT Concepts and Terminology — Read the scenario before looking for a memorised answer..
The correct answer is: DNS server is not configured or is unreachable — 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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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