This CV0-004 practice question tests your understanding of troubleshooting. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 cloud user is unable to connect to a web server VM from the internet after a security group rule was modified. The VM is running and can be pinged from other VMs in the same subnet. 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 inbound rule for HTTP/HTTPS was removed or misconfigured.
Option A is correct because the security group rule likely blocks inbound HTTP/HTTPS traffic. Option B is incorrect because DNS resolution affects hostnames, not connectivity. Option C is incorrect because routing between VMs works. Option D is incorrect because a firewall on the OS would affect all traffic, not just internet.
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 VM's local firewall is blocking the traffic.
Why it's wrong here
A local firewall would also block internal traffic.
✗
The VM's routing table is missing a default gateway.
Why it's wrong here
Internal connectivity implies routing is functional.
✓
The inbound rule for HTTP/HTTPS was removed or misconfigured.
Why this is correct
Security groups control inbound traffic; missing rule blocks internet access.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
DNS affects name resolution, not direct IP connectivity.
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 CV0-004 subnetting questions on CIDR, address ranges, and subnet selection.
Troubleshooting — This question tests Troubleshooting — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The inbound rule for HTTP/HTTPS was removed or misconfigured. — Option A is correct because the security group rule likely blocks inbound HTTP/HTTPS traffic. Option B is incorrect because DNS resolution affects hostnames, not connectivity. Option C is incorrect because routing between VMs works. Option D is incorrect because a firewall on the OS would affect all traffic, not just internet.
What should I do if I get this CV0-004 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 CV0-004 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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