The correct policy element to add is a condition using aws:SourceVpc, which restricts KMS key usage to requests originating from a specific VPC. This works because aws:SourceVpc evaluates the VPC from which the request is made, ensuring that only traffic within that network boundary can use the key, effectively implementing a KMS VPC restriction. On the AWS Certified Data Engineer Associate DEA-C01 exam, this concept tests your understanding of how to combine IAM policy conditions with KMS key policies to enforce network-level access controls, a common scenario for securing data encryption in Amazon S3. A frequent trap is confusing aws:SourceVpc with aws:SourceIp, which filters by IP address rather than VPC, or with kms:ViaService, which limits the AWS service but not the network origin. Remember the mnemonic: “VPC in the VPC condition” — if you need to lock a key to a virtual private cloud, think SourceVpc, not SourceIp.
DEA-C01 Data Security and Governance Practice Question
This DEA-C01 practice question tests your understanding of data security and governance. 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.
A company uses AWS KMS to encrypt data in Amazon S3. The security team wants to ensure that the KMS key can only be used from within the company's VPC. Which policy element should be added to the KMS key policy?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a condition using aws:SourceVpc to allow only requests from the VPC.
Option C is correct because using a condition with aws:SourceVpc restricts key usage to requests originating from a specific VPC. Option A is wrong because the Principal element specifies who can use the key, not where. Option B is wrong because aws:SourceIp is for IP addresses, not VPC. Option D is wrong because kms:ViaService restricts usage to specific AWS services, not network location.
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.
✗
Set the Principal element to restrict access to the VPC.
Why it's wrong here
Principal identifies the entity, not the network.
✗
Add a condition using aws:SourceIp to allow only IP addresses from the VPC.
Why it's wrong here
aws:SourceIp works with IP addresses, not VPC IDs.
✓
Add a condition using aws:SourceVpc to allow only requests from the VPC.
Why this is correct
This condition restricts key usage to the specified VPC.
Related concept
Static NAT maps one inside address to one outside address.
✗
Add a condition using kms:ViaService to allow only via VPC endpoints.
Why it's wrong here
kms:ViaService restricts to specific AWS services.
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 DEA-C01 NAT questions on configuration and troubleshooting.
Data Security and Governance — This question tests Data Security and Governance — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Add a condition using aws:SourceVpc to allow only requests from the VPC. — Option C is correct because using a condition with aws:SourceVpc restricts key usage to requests originating from a specific VPC. Option A is wrong because the Principal element specifies who can use the key, not where. Option B is wrong because aws:SourceIp is for IP addresses, not VPC. Option D is wrong because kms:ViaService restricts usage to specific AWS services, not network location.
What should I do if I get this DEA-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 DEA-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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