Quick Answer
The answer is CodeDeployDefault.OneAtATime, because this predefined deployment configuration deploys the application to a single EC2 instance at a time within the Auto Scaling group, pausing to perform health checks on that batch before proceeding to the next. This ensures that if a deployment fails, only one instance is impacted, aligning perfectly with the requirement for batched, health-checked rollouts. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this question tests your understanding of CodeDeploy’s built-in configurations and their behavior with Auto Scaling groups—a common scenario where you must choose between AllAtOnce, HalfAtATime, and OneAtATime. The trap is selecting HalfAtATime, which deploys to 50% of instances simultaneously, or AllAtOnce, which risks full downtime. Remember the memory tip: “OneAtATime is the cautious climb—one step, check your footing, then the next.”
This SOA-C02 practice question tests your understanding of deployment, provisioning, and automation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 SysOps administrator needs to deploy an application to a set of EC2 instances in an Auto Scaling group. The deployment must be performed in batches, with each batch health-checked before proceeding. Which AWS CodeDeploy deployment configuration should be used?
CodeDeployDefault.OneAtATime
OneAtATime deploys to one instance at a time, with health checks between each.
CodeDeployDefault.AllAtOnce
Why wrong: AllAtOnce deploys to all instances at once, not in batches.
CodeDeployDefault.HalfAtATime
Why wrong: HalfAtATime deploys to half the instances at a time, not one by one.
CodeDeployDefault.Custom
Why wrong: Custom requires user-defined configuration, but the scenario fits the predefined OneAtATime.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
CodeDeployDefault.OneAtATime
CodeDeploy has predefined deployment configurations. 'CodeDeployDefault.OneAtATime' deploys one instance at a time, allowing health checks. 'AllAtOnce' deploys to all simultaneously, 'HalfAtATime' deploys to half, and 'Custom' is a user-defined configuration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
CodeDeployDefault.OneAtATime
Why this is correct
OneAtATime deploys to one instance at a time, with health checks between each.
Related concept
Read the scenario before looking for a memorised answer.
CodeDeployDefault.AllAtOnce
Why it's wrong here
AllAtOnce deploys to all instances at once, not in batches.
CodeDeployDefault.HalfAtATime
Why it's wrong here
HalfAtATime deploys to half the instances at a time, not one by one.
CodeDeployDefault.Custom
Why it's wrong here
Custom requires user-defined configuration, but the scenario fits the predefined OneAtATime.
Common exam traps
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.
Trap categories for this question
Scenario analysis trap
Custom requires user-defined configuration, but the scenario fits the predefined OneAtATime.
Detailed technical explanation
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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 — study guide chapter
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FAQ
Deployment, Provisioning, and Automation — This question tests Deployment, Provisioning, and Automation — Read the scenario before looking for a memorised answer..
The correct answer is: CodeDeployDefault.OneAtATime — CodeDeploy has predefined deployment configurations. 'CodeDeployDefault.OneAtATime' deploys one instance at a time, allowing health checks. 'AllAtOnce' deploys to all simultaneously, 'HalfAtATime' deploys to half, and 'Custom' is a user-defined configuration.
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.
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A SysOps administrator needs to deploy a new application version to an Auto Scaling group without causing any downtime. The application runs on EC2 instances behind an Application Load Balancer. Which deployment method should the administrator use?
easyWhy C: Option C is correct because a rolling update with a batch size of 1 instance at a time minimizes impact and can be done without downtime if health checks are configured. Option A is incorrect because it does not use Auto Scaling. Option B is incorrect because it terminates all instances at once. Option D is incorrect because immutable updates launch new instances in a new Auto Scaling group, which is also zero-downtime but not the only option.
Last reviewed: Jun 20, 2026
This SOA-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 SOA-C02 exam.
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