The answer is a conflict between the minimum healthy hosts setting and the deployment group size. With a minimum healthy hosts of 100%, CodeDeploy requires that all instances remain available throughout the deployment, but the `CodeDeployDefault.OneAtATime` configuration updates only one host at a time. If the deployment group contains only a single instance, taking that instance out of service to deploy the new revision violates the 100% healthy hosts requirement, causing the insufficient capacity error. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how CodeDeploy’s health thresholds interact with fleet size—a common trap is confusing this capacity error with target group health checks or agent issues. Remember the memory tip: “One host, one hundred percent healthy—no room to deploy.”
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 CodePipeline for CI/CD. During a production deployment, the pipeline fails at the 'Deploy' stage with an error: 'The deployment failed because the deployment group does not have enough capacity to handle the deployment.' The engineer checks the CodeDeploy deployment group and sees that it is configured with a minimum healthy hosts of 100% and a deployment configuration of 'CodeDeployDefault.OneAtATime'. 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.
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 group has only one instance, and the minimum healthy hosts setting prevents the deployment.
Option B is correct because with a minimum healthy hosts of 100%, CodeDeploy requires that all hosts remain healthy during deployment. The OneAtATime configuration updates only one host at a time, but if the deployment group has only one instance, taking it out of service violates the minimum healthy hosts. Option A is wrong because the error is about capacity, not target group health. Option C is wrong because CodeDeploy agent issues would cause a different error. Option D is wrong because the deployment configuration is correct for rolling updates.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 'OneAtATime' is not compatible with the deployment group.
Why it's wrong here
OneAtATime is compatible but requires enough instances to maintain minimum healthy hosts.
✗
The target group health check is misconfigured, causing all instances to be unhealthy.
Why it's wrong here
Health check misconfigurations would cause a different error about unhealthy instances.
✗
The CodeDeploy agent on the instances is not running.
Why it's wrong here
This would cause a different error about agent not responding.
✓
The deployment group has only one instance, and the minimum healthy hosts setting prevents the deployment.
Why this is correct
With one instance and min healthy hosts 100%, taking that instance out of service violates the constraint.
Clue confirmation
The clue words "most likely", "minimum / minimize" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. 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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DOP-C02 NAT questions on configuration and troubleshooting.
Incident and Event Response — This question tests Incident and Event Response — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The deployment group has only one instance, and the minimum healthy hosts setting prevents the deployment. — Option B is correct because with a minimum healthy hosts of 100%, CodeDeploy requires that all hosts remain healthy during deployment. The OneAtATime configuration updates only one host at a time, but if the deployment group has only one instance, taking it out of service violates the minimum healthy hosts. Option A is wrong because the error is about capacity, not target group health. Option C is wrong because CodeDeploy agent issues would cause a different error. Option D is wrong because the deployment configuration is correct for rolling updates.
What should I do if I get this DOP-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DOP-C02 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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