- A
DHCP
Why wrong: DHCP assigns IP settings; the user has a valid IP and can ping, so DHCP is working.
- B
DNS
DNS resolves domain names to IPs. The user can ping by IP but not by name, so DNS is likely misconfigured or not responding on that machine.
- C
NAT
Why wrong: NAT is a router function; if it were failing, all devices would be affected, not just this one.
- D
Proxy
Why wrong: A proxy server could cause this, but it's less common in small networks; DNS is the more direct cause given the symptoms.
Question 661 of 1,020
DNS Failure: When Ping Works but Websites Don't Load
This 220-1201 practice question tests your understanding of network services. 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 complains that they cannot access any websites, but they can ping external IP addresses like 8.8.8.8 successfully. Other devices on the same network work fine. Which network service is most likely failing on this user's computer?
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.
Quick Answer
The answer is DNS, as the ability to ping external IP addresses like 8.8.8.8 confirms that the network stack, IP configuration, and routing are all functional, while the failure to load websites points directly to a breakdown in name resolution. DNS is the service responsible for translating human-readable domain names into machine-readable IP addresses; when it fails locally, the computer cannot resolve website names even though it can reach those IPs directly. On the CompTIA A+ Core 1 220-1201 exam, this scenario is a classic troubleshooting question designed to test your understanding of the OSI model’s application layer versus the network layer—ping works at Layer 3 (IP), but web browsing requires Layer 7 (DNS). A common trap is to suspect DHCP or NAT, but since other devices on the same network work fine, the issue is isolated to this computer’s DNS configuration. Remember the memory tip: “Ping by IP, fail by name—DNS is the one to blame.”
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
✓
DNS
The user can ping external IP addresses (e.g., 8.8.8.8) successfully, which confirms that IP connectivity, routing, and NAT are working. However, they cannot access websites by name, which requires DNS resolution to translate domain names into IP addresses. Since other devices on the same network work fine, the issue is isolated to this computer's DNS client configuration or service, making DNS the most likely failing service.
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.
- ✗
DHCP
Why it's wrong here
DHCP assigns IP settings; the user has a valid IP and can ping, so DHCP is working.
- ✓
DNS
Why this is correct
DNS resolves domain names to IPs. The user can ping by IP but not by name, so DNS is likely misconfigured or not responding on that machine.
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.
- ✗
NAT
Why it's wrong here
NAT is a router function; if it were failing, all devices would be affected, not just this one.
- ✗
Proxy
Why it's wrong here
A proxy server could cause this, but it's less common in small networks; DNS is the more direct cause given the symptoms.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA A+ often tests the distinction between IP connectivity (ping to IP) and name resolution (ping to hostname), trapping candidates who confuse a working ping to an IP with full internet functionality, when DNS is actually the broken link.
Detailed technical explanation
How to think about this question
DNS resolution typically uses UDP port 53 for queries, and the client's DNS server addresses are often obtained via DHCP or configured manually. A common subtle issue is that the DNS client service on Windows (dnscache) may cache stale or incorrect records; flushing the cache with 'ipconfig /flushdns' can resolve such problems. In real-world scenarios, a misconfigured hosts file or a third-party security software blocking DNS queries can also cause this exact symptom.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Network Services — This question tests Network Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: DNS — The user can ping external IP addresses (e.g., 8.8.8.8) successfully, which confirms that IP connectivity, routing, and NAT are working. However, they cannot access websites by name, which requires DNS resolution to translate domain names into IP addresses. Since other devices on the same network work fine, the issue is isolated to this computer's DNS client configuration or service, making DNS the most likely failing service.
What should I do if I get this 220-1201 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 →
Same concept, more angles
2 more ways this is tested on 220-1201
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. A user reports that they cannot access any websites, but they can ping the IP address of a public DNS server (8.8.8.8). What is the most likely misconfigured network service?
easy- A.DHCP
- ✓ B.DNS
- C.NAT
- D.Proxy
Why B: The user can ping 8.8.8.8, confirming that IP connectivity and routing are working, but cannot access websites by name. This indicates that the system cannot resolve domain names to IP addresses, which is the function of DNS. A misconfigured DNS server address (e.g., pointing to a non-existent or unreachable DNS server) would cause this exact symptom.
Variation 2. A user reports that they can access internal resources using IP addresses but cannot access them using hostnames. Other users on the same network have no issues. What is the most likely cause?
medium- A.The DHCP server is out of addresses
- B.The DNS server is down
- ✓ C.The user's DNS settings are incorrect
- D.The router's NAT is misconfigured
Why C: The ability to use IP addresses but not hostnames points to a DNS resolution problem on the user's device. This could be due to a misconfigured DNS server address in the network settings or a local hosts file issue. Other users working normally suggests the problem is client-specific.
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Last reviewed: Jul 4, 2026
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