The correct answer is that the EC2 instance lacks a SecurityGroup or SecurityGroupIds property referencing the security group. In CloudFormation, a DependsOn attribute only dictates the order of resource creation—it does not establish any logical or network attachment between resources. Without explicitly specifying the security group under the instance’s SecurityGroupIds property, the security group is created but never associated with the EC2 instance, leaving it unapplied. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of the difference between resource dependencies and resource associations, a common trap where engineers assume DependsOn also attaches resources. A key memory tip: DependsOn is a timing tool, not a wiring tool—think of it as “create after” rather than “attach to.”
DOP-C02 Configuration Management and IaC Practice Question
This DOP-C02 practice question tests your understanding of configuration management and iac. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 DevOps engineer creates the CloudFormation template shown in the exhibit. When the stack is created, the EC2 instance is launched but the security group is not applied to the instance. What is the likely cause?
The security group resource is missing a VpcId property, so it is not created in the same VPC as the instance.
Why wrong: B: The security group will be created in the default VPC if VpcId is not specified, but the instance also goes to the default VPC, so that is not the issue.
B
The instance does not have a SecurityGroup or SecurityGroupIds property referencing the security group.
D: The instance properties must include SecurityGroupIds or SecurityGroups to attach the group; DependsOn only controls creation order.
C
The security group is created after the instance, so the instance cannot reference it.
Why wrong: C: DependsOn ensures the security group is created first.
D
The DependsOn clause should be removed because it causes a circular dependency.
Why wrong: A: There is no circular dependency; DependsOn is used correctly but does not attach the group.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The instance does not have a SecurityGroup or SecurityGroupIds property referencing the security group.
Option D is correct because the template does not associate the security group with the instance; the DependsOn only ensures creation order, but does not attach the group. Option A is wrong because DependsOn does not automatically attach. Option B is wrong because the security group is created. Option C is wrong because the security group is created first due to DependsOn, but still not attached.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 security group resource is missing a VpcId property, so it is not created in the same VPC as the instance.
Why it's wrong here
B: The security group will be created in the default VPC if VpcId is not specified, but the instance also goes to the default VPC, so that is not the issue.
✓
The instance does not have a SecurityGroup or SecurityGroupIds property referencing the security group.
Why this is correct
D: The instance properties must include SecurityGroupIds or SecurityGroups to attach the group; DependsOn only controls creation order.
Related concept
Read the scenario before looking for a memorised answer.
✗
The security group is created after the instance, so the instance cannot reference it.
Why it's wrong here
C: DependsOn ensures the security group is created first.
✗
The DependsOn clause should be removed because it causes a circular dependency.
Why it's wrong here
A: There is no circular dependency; DependsOn is used correctly but does not attach the group.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
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.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which DOP-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.
Configuration Management and IaC — This question tests Configuration Management and IaC — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The instance does not have a SecurityGroup or SecurityGroupIds property referencing the security group. — Option D is correct because the template does not associate the security group with the instance; the DependsOn only ensures creation order, but does not attach the group. Option A is wrong because DependsOn does not automatically attach. Option B is wrong because the security group is created. Option C is wrong because the security group is created first due to DependsOn, but still not attached.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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