The answer is to use an IAM policy that denies the ec2:RunInstances action unless the AMI ID matches the approved one. This is the most efficient method because it leverages AWS Identity and Access Management to enforce a condition at the API level, blocking any non-compliant EC2 launch before it can occur, rather than detecting or remediating it after the fact. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this question tests your understanding of preventive versus detective controls—a common trap is choosing AWS Config or CloudTrail, which only report or log violations but do not prevent them. Remember that IAM policies with condition keys like ec2:ImageId provide a hard block, making them the fastest and most direct enforcement mechanism. A useful memory tip: "Deny before you detect"—if you need to enforce an AMI, use IAM to deny non-approved IDs at the gate, not Config to catch them in the yard.
SOA-C02 Deployment, Provisioning, and Automation Practice Question
This SOA-C02 practice question tests your understanding of deployment, provisioning, and automation. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
An organization needs to enforce that all Amazon EC2 instances launched in a specific AWS account are created from a baseline Amazon Machine Image (AMI) that includes required security patches. The AMI ID is ami-0abcdef1234567890. What is the MOST efficient way to enforce this requirement?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use an IAM policy that denies the ec2:RunInstances action unless the AMI ID matches the approved one.
Option C is correct because using an IAM policy with a condition that denies launching instances unless the specified AMI ID is used is the most efficient way to enforce the requirement. Option A is incorrect because CloudTrail logs after the fact and does not prevent launches. Option B is incorrect because Config rules can detect non-compliance but do not block the action. Option D is incorrect because Lambda would need to be triggered and could delay the launch.
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.
✗
Use an AWS Config rule to mark non-compliant instances and automatically terminate them.
Why it's wrong here
Config can detect but not block the launch in real-time.
✗
Use an AWS Lambda function that is triggered by EC2 launch events to terminate non-compliant instances.
Why it's wrong here
This is reactive and may incur costs and delays.
✗
Use AWS CloudTrail to monitor and alert on any instance launched with a different AMI.
Why it's wrong here
CloudTrail logs actions, but does not prevent them.
✓
Use an IAM policy that denies the ec2:RunInstances action unless the AMI ID matches the approved one.
Why this is correct
This prevents any non-compliant launch attempt.
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 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 SOA-C02 NAT questions on configuration and troubleshooting.
Deployment, Provisioning, and Automation — This question tests Deployment, Provisioning, and Automation — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use an IAM policy that denies the ec2:RunInstances action unless the AMI ID matches the approved one. — Option C is correct because using an IAM policy with a condition that denies launching instances unless the specified AMI ID is used is the most efficient way to enforce the requirement. Option A is incorrect because CloudTrail logs after the fact and does not prevent launches. Option B is incorrect because Config rules can detect non-compliance but do not block the action. Option D is incorrect because Lambda would need to be triggered and could delay the launch.
What should I do if I get this SOA-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 SOA-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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