This DVA-C02 practice question tests your understanding of development with aws services. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Refer to the exhibit. A developer attached the IAM policy to a Lambda function's execution role. The function reads items from a DynamoDB table that uses AWS KMS customer managed key (CMK) for encryption at rest. When the function tries to read an item, it receives an access denied error. What is the cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy allows kms:Decrypt on all resources but the CMK key policy may not grant access.
The IAM policy grants kms:Decrypt on all resources, but DynamoDB uses AWS KMS customer managed keys (CMKs) for encryption at rest. Even if the IAM policy allows the action, the CMK's key policy must also grant the Lambda execution role access to use the key. If the key policy does not include a statement allowing the Lambda role to perform kms:Decrypt, the request fails with an access denied error, regardless of the IAM policy.
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 DynamoDB table is not encrypted with a KMS key.
Why it's wrong here
The exhibit implies encryption is used.
✓
The policy allows kms:Decrypt on all resources but the CMK key policy may not grant access.
Why this is correct
Even if IAM allows, the key policy must also allow the role.
Related concept
Read the scenario before looking for a memorised answer.
✗
The policy does not allow dynamodb:GetItem on the table.
Why it's wrong here
It does allow GetItem.
✗
The DynamoDB table does not exist.
Why it's wrong here
Error is access denied, not not found.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume an IAM policy allowing kms:Decrypt on all resources is sufficient, forgetting that KMS customer managed keys have their own key policies that must also grant access.
Detailed technical explanation
How to think about this question
When a DynamoDB table is encrypted with a customer managed KMS key, the service calls KMS to decrypt the table's data encryption key on each read. The KMS key policy acts as a resource-based policy that must explicitly grant the caller (the Lambda execution role) the kms:Decrypt permission. Even if the IAM policy allows kms:Decrypt on all resources, the key policy can deny access by omission or explicit deny, causing an access denied error. This is a common misconfiguration when using cross-account or cross-service KMS keys.
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.
TExam Day Tips
→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.
Quick reference
Cloud Service Model Comparison
Model
You Manage
Provider Manages
Examples
IaaS
OS, runtime, apps, data
Hardware, hypervisor, networking
EC2, Azure VMs, GCP Compute Engine
PaaS
Apps and data
OS, runtime, middleware, hardware
Elastic Beanstalk, Azure App Service
SaaS
Data and settings only
Everything else
Microsoft 365, Salesforce, Workday
FaaS / Serverless
Function code only
Infra, scaling, runtime
Lambda, Azure Functions, Cloud Run
CaaS
Containers and apps
Kubernetes, OS, hardware
EKS, AKS, GKE
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The policy allows kms:Decrypt on all resources but the CMK key policy may not grant access. — The IAM policy grants kms:Decrypt on all resources, but DynamoDB uses AWS KMS customer managed keys (CMKs) for encryption at rest. Even if the IAM policy allows the action, the CMK's key policy must also grant the Lambda execution role access to use the key. If the key policy does not include a statement allowing the Lambda role to perform kms:Decrypt, the request fails with an access denied error, regardless of the IAM policy.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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