This DVA-C02 practice question tests your understanding of deployment. 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. A key principle to apply: deploys to one instance at a time within the deployment group.. 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 developer is using AWS CodeDeploy to deploy an application to an EC2 Auto Scaling group. The deployment must ensure that a minimum number of instances are always running and healthy. The developer wants to deploy to 10 instances. Which deployment configuration should the developer use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
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
✓
CodeDeployDefault.OneAtATime
Option A, CodeDeployDefault.OneAtATime, is correct because it ensures that only one instance is updated at a time, which guarantees that a minimum number of instances (9 out of 10) remain healthy and running throughout the deployment. This configuration is ideal for maintaining high availability and meeting strict uptime requirements.
Key principle: Deploys to one instance at a time within the deployment group.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
CodeDeployDefault.OneAtATime
Why this is correct
This configuration deploys to one instance at a time, keeping the maximum number of healthy instances at any time.
Clue confirmation
The clue words "always", "minimum / minimize" in the question point toward this answer.
Related concept
Deploys to one instance at a time within the deployment group.
✗
CodeDeployDefault.AllAtOnce
Why it's wrong here
AllAtOnce deploys to all instances simultaneously, which can cause downtime if the application is not designed for zero-downtime updates.
✗
CodeDeployDefault.HalfAtATime
Why it's wrong here
HalfAtATime deploys to half the instances at a time; for 10 instances, that means 5 are updated at once, leaving only 5 healthy.
✗
CodeDeployDefault.MinHealthyHostsPercentage: 90
Why it's wrong here
This is not a predefined CodeDeploy deployment configuration name; it is a parameter within a deployment group.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the predefined deployment configurations with custom settings, assuming that 'MinHealthyHostsPercentage: 90' is a valid named configuration, when in fact it is a parameter that must be specified as part of a custom configuration, not a built-in option.
Detailed technical explanation
How to think about this question
Under the hood, CodeDeploy uses a deployment group and a deployment configuration to control the pace of updates. The OneAtATime configuration is equivalent to setting the minimum healthy hosts to 90% (for 10 instances, that means at least 9 must remain healthy), but it is a predefined named configuration that simplifies setup. In a real-world scenario, if you are deploying a critical microservice that must maintain a specific number of healthy endpoints to handle traffic, OneAtATime provides a safe, gradual rollout that minimizes risk.
KKey Concepts to Remember
Deploys to one instance at a time within the deployment group.
Ensures maximum application availability during the deployment process.
Suitable for applications requiring a high minimum number of healthy hosts.
A predefined, default deployment configuration provided by AWS CodeDeploy.
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
Deploys to one instance at a time within the deployment group.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review deploys to one instance at a time within the deployment group., then practise related DVA-C02 questions on the same topic to reinforce the concept.
Deployment — This question tests Deployment — Deploys to one instance at a time within the deployment group..
What is the correct answer to this question?
The correct answer is: CodeDeployDefault.OneAtATime — Option A, CodeDeployDefault.OneAtATime, is correct because it ensures that only one instance is updated at a time, which guarantees that a minimum number of instances (9 out of 10) remain healthy and running throughout the deployment. This configuration is ideal for maintaining high availability and meeting strict uptime requirements.
What should I do if I get this DVA-C02 question wrong?
Review deploys to one instance at a time within the deployment group., then practise related DVA-C02 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "always", "minimum / minimize". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
What is the key concept behind this question?
Deploys to one instance at a time within the deployment group.
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Question Discussion
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