This DOP-C02 practice question tests your understanding of sdlc 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.
A company uses AWS CodeDeploy to deploy an application to an Auto Scaling group. The deployment fails with the error 'The overall deployment failed because too many individual instances failed deployment, too few healthy instances are available for deployment, or some instances in your deployment group are experiencing problems.' The deployment is set to 'AllAtOnce'. The application revision is a simple index.html. 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 CodeDeploy agent is not installed or running on the EC2 instances.
Option D is correct because the CodeDeploy agent must be installed on each EC2 instance in the Auto Scaling group to receive and execute deployments. Option A is wrong because AllAtOnce means all instances deploy simultaneously. Option B is wrong because S3 permissions are needed but would cause a different error. Option C is wrong because the revision is a single file, not a zip, but CodeDeploy requires a revision format; however, the error message suggests instance failure.
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 CodeDeploy agent is not installed or running on the EC2 instances.
Why this is correct
Without the agent, instances cannot run deployment scripts.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The IAM instance profile does not have permissions to download from Amazon S3.
Why it's wrong here
While necessary, missing permissions would produce a different error.
✗
The application revision is not a compressed archive.
Why it's wrong here
CodeDeploy can deploy individual files if specified in appspec.
✗
The deployment configuration 'AllAtOnce' is incompatible with Auto Scaling groups.
Why it's wrong here
AllAtOnce is valid for Auto Scaling groups.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
SDLC Automation — This question tests SDLC Automation — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The CodeDeploy agent is not installed or running on the EC2 instances. — Option D is correct because the CodeDeploy agent must be installed on each EC2 instance in the Auto Scaling group to receive and execute deployments. Option A is wrong because AllAtOnce means all instances deploy simultaneously. Option B is wrong because S3 permissions are needed but would cause a different error. Option C is wrong because the revision is a single file, not a zip, but CodeDeploy requires a revision format; however, the error message suggests instance failure.
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". 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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