The answer is a missing CodeDeploy agent on the EC2 instance, as this is the most likely cause of an intermittent deploy failure in CodePipeline. When an EC2 instance is terminated and replaced—common in auto-scaling environments—the new instance may lack the CodeDeploy agent, causing the deployment to fail only when that specific instance is targeted. This tests your understanding of the CodePipeline-to-EC2 deployment lifecycle on the AWS Certified Developer Associate DVA-C02 exam, where a common trap is assuming the agent persists across instance replacements or blaming CodeBuild’s temporary instances. Remember that CodeBuild handles build, not deploy, and the agent must be pre-installed or bootstrapped via user data. Memory tip: “No agent, no deploy—check the instance’s health before you weep.”
DVA-C02 Deployment Practice Question
This DVA-C02 practice question tests your understanding of deployment. 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 to deploy a web application. The deployment fails intermittently during the 'Deploy' stage. The pipeline includes a step that runs a shell script on an EC2 instance. The pipeline uses a CodeBuild project for the build stage. What is the MOST likely cause of the intermittent 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The EC2 instance used for deployment does not have the CodeDeploy agent installed.
Option B is correct because if the EC2 instance is terminated or replaced, the CodeDeploy agent may not be installed, causing intermittent failures. Option A is wrong because CodeBuild uses temporary instances. Option C is wrong because CodePipeline does not require a VPC. Option D is wrong because IAM roles are not updated automatically.
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 CodeBuild project is using an outdated build image.
Why it's wrong here
Outdated image would cause consistent failures.
✓
The EC2 instance used for deployment does not have the CodeDeploy agent installed.
Why this is correct
Missing agent causes intermittent failures if instance is replaced.
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 pipeline is not configured to use a VPC.
Why it's wrong here
VPC configuration is not required for CodePipeline.
✗
The IAM role for CodePipeline does not have permissions to deploy.
Why it's wrong here
Permissions issue would cause consistent failure.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 DVA-C02 NAT questions on configuration and troubleshooting.
Deployment — This question tests Deployment — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The EC2 instance used for deployment does not have the CodeDeploy agent installed. — Option B is correct because if the EC2 instance is terminated or replaced, the CodeDeploy agent may not be installed, causing intermittent failures. Option A is wrong because CodeBuild uses temporary instances. Option C is wrong because CodePipeline does not require a VPC. Option D is wrong because IAM roles are not updated automatically.
What should I do if I get this DVA-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 DVA-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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