- A
The application revision is missing from the S3 bucket.
Why wrong: A missing revision would cause a download failure, not a script exit code error.
- B
The BeforeInstall script has a bug that causes it to exit with a non-zero status.
Lifecycle event scripts must exit with zero to indicate success; a non-zero exit indicates failure.
- C
The IAM instance profile does not have permissions to call CodeDeploy APIs.
Why wrong: Permissions issues would prevent the agent from registering with CodeDeploy, not cause a script to fail.
- D
The CodeDeploy agent is not running on the instances.
Why wrong: If the agent were not running, the deployment would not proceed to lifecycle events.
Question 707 of 1,616
CodeDeploy BeforeInstall Script Failure: Non-Zero Exit
This DVA-C02 practice question tests your understanding of development with aws 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 company is using AWS CodeDeploy to deploy an application to an Auto Scaling group. The deployment fails with the error 'The overall deployment failed because too many individual instances failed to deploy.' The CodeDeploy agent logs show that the BeforeInstall lifecycle event script returned a non-zero exit code. 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 BeforeInstall script has a bug that causes it to exit with a non-zero status.
Option B is correct because the error message explicitly states that the CodeDeploy agent logs show the BeforeInstall lifecycle event script returned a non-zero exit code. This directly indicates that the script itself failed during execution, which is the most likely cause of the deployment failure. The BeforeInstall script is a custom script run by the CodeDeploy agent on each instance, and a non-zero exit code signals an error condition that halts the deployment for that instance.
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 application revision is missing from the S3 bucket.
Why it's wrong here
A missing revision would cause a download failure, not a script exit code error.
- ✓
The BeforeInstall script has a bug that causes it to exit with a non-zero status.
Why this is correct
Lifecycle event scripts must exit with zero to indicate success; a non-zero exit indicates failure.
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 IAM instance profile does not have permissions to call CodeDeploy APIs.
Why it's wrong here
Permissions issues would prevent the agent from registering with CodeDeploy, not cause a script to fail.
- ✗
The CodeDeploy agent is not running on the instances.
Why it's wrong here
If the agent were not running, the deployment would not proceed to lifecycle events.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse a script failure (non-zero exit code) with infrastructure or permission issues, but the question explicitly provides the agent log detail pointing to the BeforeInstall script, making the script bug the direct and most likely cause.
Detailed technical explanation
How to think about this question
CodeDeploy lifecycle events (BeforeInstall, AfterInstall, ApplicationStart, etc.) are executed sequentially by the agent, and each script must exit with code 0 to proceed. A non-zero exit code (e.g., 1, 2, or 127) causes the agent to mark the deployment as failed for that instance. Common causes include syntax errors in the script, missing dependencies, or environment variables not set correctly. The agent logs the exact exit code and stderr output, which is critical for debugging.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The BeforeInstall script has a bug that causes it to exit with a non-zero status. — Option B is correct because the error message explicitly states that the CodeDeploy agent logs show the BeforeInstall lifecycle event script returned a non-zero exit code. This directly indicates that the script itself failed during execution, which is the most likely cause of the deployment failure. The BeforeInstall script is a custom script run by the CodeDeploy agent on each instance, and a non-zero exit code signals an error condition that halts the deployment for that instance.
What should I do if I get this DVA-C02 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.
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Last reviewed: Jul 4, 2026
This DVA-C02 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 DVA-C02 exam.
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