The answer is that the deployment fails because CodeDeployDefault.OneAtATime only deploys to a single instance at a time, and when that first instance fails, there are no other healthy instances to continue the deployment. This configuration means the deployment process stops immediately on the first failure, as the Auto Scaling group’s second instance is never reached. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of how deployment configurations interact with minimum healthy instance thresholds—a common trap is assuming the second instance will automatically take over. Remember that with OneAtATime, the deployment is serial and brittle: if the first instance fails, the entire deployment fails, regardless of how many total instances exist. A useful memory tip is “OneAtATime = One failure stops the line.”
SOA-C02 Deployment, Provisioning, and Automation Practice Question
This SOA-C02 practice question tests your understanding of deployment, provisioning, and automation. 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.
Network Topology
A SysOps administrator sees the deployment failure shown in the exhibit. The deployment group has a minimum of 1 healthy instance. The Auto Scaling group has 2 instances. What is the most likely cause of the failure?
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.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The deployment configuration only deploys to one instance at a time, and that instance failed.
With CodeDeployDefault.OneAtATime, only one instance is deployed at a time. If that instance fails, the deployment fails because there are no other instances to deploy (the other instance is not deployed yet). Option A is correct. Option B is wrong because the deployment configuration is correct. Option C is wrong because the health check grace period is not relevant. Option D is wrong because the deployment group has 2 instances, which is enough.
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 deployment configuration only deploys to one instance at a time, and that instance failed.
Why this is correct
OneAtATime deploys to one instance; if it fails, the deployment stops.
Clue confirmation
The clue words "most likely", "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Auto Scaling group's health check grace period is too long.
Why it's wrong here
The grace period does not cause deployment failure.
✗
The deployment group does not have enough instances.
Why it's wrong here
Two instances are sufficient for OneAtATime.
✗
The deployment configuration is set to deploy to all instances at once.
Why it's wrong here
OneAtATime deploys to one instance at a time.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which SOA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Deployment, Provisioning, and Automation — This question tests Deployment, Provisioning, and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The deployment configuration only deploys to one instance at a time, and that instance failed. — With CodeDeployDefault.OneAtATime, only one instance is deployed at a time. If that instance fails, the deployment fails because there are no other instances to deploy (the other instance is not deployed yet). Option A is correct. Option B is wrong because the deployment configuration is correct. Option C is wrong because the health check grace period is not relevant. Option D is wrong because the deployment group has 2 instances, which is enough.
What should I do if I get this SOA-C02 question wrong?
Identify which SOA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely", "minimum / minimize". 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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