The correct answer is that the policy allows only the specified KMS actions on the key when the request originates from the RDS service via the specific VPC endpoint. This is because the IAM policy condition for VPC endpoint and service principal for KMS uses both the `aws:SourceVpce` and `aws:SourceService` condition keys to enforce that the request must come through that exact VPC endpoint and from the RDS service principal, preventing access from other sources or endpoints. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how to restrict KMS key access to a specific VPC endpoint and service, a common trap being that candidates mistakenly think the VPC endpoint condition alone is sufficient—it is not, as the service principal condition is also required to ensure the request originates from RDS. A helpful memory tip is "Endpoint plus Service equals Secure," reminding you that both conditions must be present to properly scope the policy.
DBS-C01 Database Security Practice Question
This DBS-C01 practice question tests your understanding of database security. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Allows only the specified KMS actions on the key when the request originates from the RDS service via the specific VPC endpoint.
Option B is correct. The policy allows the specified KMS actions only when the request comes through the specified VPC endpoint and via the RDS service. Option A is wrong because it only allows through VPC endpoint. Option C is wrong because it does not allow all KMS actions. Option D is wrong because it does not allow all resources.
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.
✗
Allows all KMS actions on the key only when the request comes from RDS.
Why it's wrong here
It also requires the request to come through the VPC endpoint.
✗
Allows all KMS actions on the specified key from any source.
Why it's wrong here
The condition restricts to VPC endpoint and RDS service.
✗
Allows the specified KMS actions on all KMS keys in the account.
Why it's wrong here
The resource is specific to one key.
✓
Allows only the specified KMS actions on the key when the request originates from the RDS service via the specific VPC endpoint.
Why this is correct
The policy has conditions limiting to RDS and VPC endpoint.
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 DBS-C01 NAT questions on configuration and troubleshooting.
Database Security — This question tests Database Security — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Allows only the specified KMS actions on the key when the request originates from the RDS service via the specific VPC endpoint. — Option B is correct. The policy allows the specified KMS actions only when the request comes through the specified VPC endpoint and via the RDS service. Option A is wrong because it only allows through VPC endpoint. Option C is wrong because it does not allow all KMS actions. Option D is wrong because it does not allow all resources.
What should I do if I get this DBS-C01 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 DBS-C01 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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