- A
The laptop's DNS server address is set to a public DNS like 8.8.8.8
Why wrong: Public DNS addresses typically work fine and would not prevent internet access; they might even improve performance.
- B
The laptop's default gateway address is incorrect
A wrong default gateway prevents the device from sending traffic outside its local subnet, which is exactly what is described.
- C
The laptop's IP address is set to a static address in the same subnet as the router
Why wrong: A static IP in the same subnet would still allow internet access if the gateway is correct; this would not cause the issue.
- D
The office Wi-Fi network is using a different SSID than expected
Why wrong: If the laptop connects to Wi-Fi, it is already using the correct SSID; a different SSID would prevent connection entirely.
Quick Answer
The answer is an incorrect default gateway address, because when a laptop connects to Wi-Fi but not the internet, it indicates successful local network access but a failure in routing traffic beyond the local subnet. The default gateway is the router that forwards packets from your local network to external networks, so a mismatched or missing gateway address prevents the laptop from reaching the internet while still allowing it to communicate with other devices on the same LAN. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to differentiate between layer 2 (local connectivity) and layer 3 (routing) issues; a common trap is blaming DNS or an IP conflict, but those typically cause name resolution failures or address duplication errors, not a complete inability to reach external sites. To remember this, think of the default gateway as the “exit door” for your network—if the laptop has the wrong door number, it can still talk to neighbors in the same room but can never leave the building.
220-1201 Network Configuration Concepts Practice Question
This 220-1201 practice question tests your understanding of network configuration concepts. 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 customer reports that their laptop connects to the office Wi-Fi but cannot access the internet. Other devices on the same network work fine. What is the most likely cause of this 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.
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 laptop's default gateway address is incorrect
This question tests understanding of common network configuration issues. A mismatched gateway address is the most likely cause because the device can connect locally but cannot route traffic to the internet. Incorrect DNS or IP address conflicts usually cause different symptoms.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 laptop's DNS server address is set to a public DNS like 8.8.8.8
Why it's wrong here
Public DNS addresses typically work fine and would not prevent internet access; they might even improve performance.
- ✓
The laptop's default gateway address is incorrect
Why this is correct
A wrong default gateway prevents the device from sending traffic outside its local subnet, which is exactly what is described.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
CIDR notation defines the prefix length.
- ✗
The laptop's IP address is set to a static address in the same subnet as the router
Why it's wrong here
A static IP in the same subnet would still allow internet access if the gateway is correct; this would not cause the issue.
- ✗
The office Wi-Fi network is using a different SSID than expected
Why it's wrong here
If the laptop connects to Wi-Fi, it is already using the correct SSID; a different SSID would prevent connection entirely.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
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Network Configuration Concepts — study guide chapter
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Network Configuration Concepts — This question tests Network Configuration Concepts — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The laptop's default gateway address is incorrect — This question tests understanding of common network configuration issues. A mismatched gateway address is the most likely cause because the device can connect locally but cannot route traffic to the internet. Incorrect DNS or IP address conflicts usually cause different symptoms.
What should I do if I get this 220-1201 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
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?
CIDR notation defines the prefix length.
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Last reviewed: Jun 18, 2026
This 220-1201 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 220-1201 exam.
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