DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. 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 uses AWS Systems Manager Patch Manager to patch EC2 instances. During a patching window, some instances fail to apply patches. The engineer checks the SSM Agent logs and sees 'ERROR: Failed to download patch files from the source.' 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 security group or NACL is blocking outbound HTTPS traffic (port 443).
The error 'Failed to download patch files from the source' indicates that the SSM Agent on the instance cannot reach the patch source repositories (e.g., Windows Update, Amazon Linux repos, or custom patch sources). Systems Manager Patch Manager requires outbound HTTPS (port 443) connectivity to download patch metadata and binaries. If a security group or NACL blocks this traffic, the download fails, producing this exact error in the agent logs.
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 IAM instance profile does not grant ssm:UpdateInstanceInformation.
Why it's wrong here
That permission is needed for registration, not patch download.
✗
The SSM Agent is outdated.
Why it's wrong here
Outdated agent might cause different errors, but download failure is usually network.
✗
The patch baseline is configured incorrectly.
Why it's wrong here
Patch baseline defines approved patches; download failure is separate.
✓
The security group or NACL is blocking outbound HTTPS traffic (port 443).
Why this is correct
Patch download requires outbound HTTPS to patch repositories.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the error is due to IAM permissions or patch baseline misconfiguration, overlooking that the specific 'Failed to download' message is a classic symptom of network egress blocking, not authorization or configuration issues.
Detailed technical explanation
How to think about this question
Patch Manager uses the SSM Agent to invoke the system's native package manager (e.g., yum, apt, Windows Update API) which fetches patches from external repositories over HTTPS (TCP 443). If the instance is in a private subnet without a NATgateway, VPC endpoint, or proxy configured, outbound traffic is blocked, causing the download failure. The error is logged by the SSM Agent when it cannot retrieve the patch content, not when it fails to apply a patch that was already downloaded.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The security group or NACL is blocking outbound HTTPS traffic (port 443). — The error 'Failed to download patch files from the source' indicates that the SSM Agent on the instance cannot reach the patch source repositories (e.g., Windows Update, Amazon Linux repos, or custom patch sources). Systems Manager Patch Manager requires outbound HTTPS (port 443) connectivity to download patch metadata and binaries. If a security group or NACL blocks this traffic, the download fails, producing this exact error in the agent logs.
What should I do if I get this DOP-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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Question Discussion
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