The correct change is to set the Principal to the specific AWS account ID of the allowed account. This works because an S3 bucket policy with Principal set to "*" grants public access to everyone, while restricting the Principal to a single AWS account ID ensures that only authenticated users from that account can read objects, effectively blocking all anonymous traffic. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how bucket policy principals control access scope—a common trap is confusing the Principal element with the Condition element, where specifying an account ID in a Condition without changing the Principal still leaves the bucket publicly accessible. Remember that Principal "*" means "anyone," even if you add a Condition; to truly restrict access, the Principal must be the specific account. A useful memory tip is: "Principal is the who, Condition is the when and how—fix the who first."
DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. 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.
The CloudFormation template in the exhibit deploys an S3 bucket with a bucket policy. After deployment, the DevOps team discovers that the bucket is publicly accessible. Which change should be made to prevent public access while allowing only authenticated users from a specific AWS account to read objects?
Change the Principal to the AWS account ID of the allowed account
Restricts access to a specific account.
C
Change the Principal to "*" and add a condition for aws:SourceIp
Why wrong: Principal "*" is still public.
D
Set the bucket's 'BlockPublicAccess' property to true
Why wrong: This is a valid change but the question asks to modify the policy to allow specific account; blocking public access would also block the intended access if not combined with explicit allow.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the Principal to the AWS account ID of the allowed account
Option C is correct because restricting the Principal to a specific AWS account prevents public access. Option A is wrong because public access is enabled by Principal "*". Option B is wrong because blocking public access at the account level is an alternative, but the question asks to change the template. Option D is wrong because blocking public access on the bucket is another approach, but the template change is required.
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.
✗
Enable AWS Organizations to block public access
Why it's wrong here
Not a template change.
✓
Change the Principal to the AWS account ID of the allowed account
Why this is correct
Restricts access to a specific account.
Related concept
Static NAT maps one inside address to one outside address.
✗
Change the Principal to "*" and add a condition for aws:SourceIp
Why it's wrong here
Principal "*" is still public.
✗
Set the bucket's 'BlockPublicAccess' property to true
Why it's wrong here
This is a valid change but the question asks to modify the policy to allow specific account; blocking public access would also block the intended access if not combined with explicit allow.
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.
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: Change the Principal to the AWS account ID of the allowed account — Option C is correct because restricting the Principal to a specific AWS account prevents public access. Option A is wrong because public access is enabled by Principal "*". Option B is wrong because blocking public access at the account level is an alternative, but the question asks to change the template. Option D is wrong because blocking public access on the bucket is another approach, but the template change is required.
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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