This PAS-C01 practice question tests your understanding of technology. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Network Topology
Refer to the exhibit. A CloudFormation stack creation failed with the message 'WaitCondition received failed signal'. 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.
Network Topology
A
The security group rules are blocking the cfn-signal communication
Why wrong: cfn-signal uses HTTPS to CloudFormation endpoint, not blocked by typical security groups.
B
The stack creation timed out after 1 hour
Why wrong: Timeout would show a different status reason.
C
The script executed via cfn-signal failed to complete successfully
The WaitCondition expects a success signal; failure indicates script error.
D
The EC2 instance type is not supported in the region
Why wrong: That would be a different error, not a signal failure.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The script executed via cfn-signal failed to complete successfully
The `WaitCondition` resource in CloudFormation is designed to pause stack creation until it receives a success signal from a resource, typically an EC2 instance running a cfn-init script. The 'WaitCondition received failed signal' error indicates that the signal sent was explicitly a failure signal (e.g., via `cfn-signal --exit-code 1`), not that the signal was lost or blocked. This most commonly occurs when the script executed by cfn-init or a user-data script encounters an error and exits with a non-zero exit code, causing cfn-signal to send a failure signal to the WaitCondition.
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 security group rules are blocking the cfn-signal communication
Why it's wrong here
cfn-signal uses HTTPS to CloudFormation endpoint, not blocked by typical security groups.
✗
The stack creation timed out after 1 hour
Why it's wrong here
Timeout would show a different status reason.
✓
The script executed via cfn-signal failed to complete successfully
Why this is correct
The WaitCondition expects a success signal; failure indicates script error.
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.
✗
The EC2 instance type is not supported in the region
Why it's wrong here
That would be a different error, not a signal failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The most common pitfall is confusing a timeout (no signal received) with a failed signal (signal with non-zero exit code). Candidates often assume network issues like security groups blocking cfn-signal, but the error explicitly states a failed signal was received, indicating a script error on the instance.
Trap categories for this question
Command / output trap
Timeout would show a different status reason.
Detailed technical explanation
How to think about this question
The cfn-signal utility sends a success or failure signal to the WaitCondition by making an HTTP PUT request to the CloudFormation pre-signed URL stored in the `AWS::CloudFormation::WaitConditionHandle` resource. The exit code of the script determines the signal: exit code 0 sends a success signal, while any non-zero exit code sends a failure signal. In real-world scenarios, common script failures include misconfigured package installations, incorrect file paths in `files` section, or services failing to start, all of which result in a non-zero exit code and the exact error message seen.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
Technology — This question tests Technology — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The script executed via cfn-signal failed to complete successfully — The `WaitCondition` resource in CloudFormation is designed to pause stack creation until it receives a success signal from a resource, typically an EC2 instance running a cfn-init script. The 'WaitCondition received failed signal' error indicates that the signal sent was explicitly a failure signal (e.g., via `cfn-signal --exit-code 1`), not that the signal was lost or blocked. This most commonly occurs when the script executed by cfn-init or a user-data script encounters an error and exits with a non-zero exit code, causing cfn-signal to send a failure signal to the WaitCondition.
What should I do if I get this PAS-C01 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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PAS-C01 practice question is part of Courseiva's free Amazon Web Services 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 PAS-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.