Question 767 of 724
DVA-C02 Security Practice Question
An application running on an EC2 instance needs to access a DynamoDB table. The instance is in a private subnet without internet access. Which method should be used to grant the instance access to DynamoDB securely?
⚠ Common exam trap
Candidates often confuse security groups with network routing, assuming that allowing outbound traffic to DynamoDB's IP range is sufficient, but without a VPC endpoint or internet gateway, the traffic has no route to reach the DynamoDB service.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a VPC endpoint for DynamoDB and attach an IAM role to the instance
A VPC Gateway Endpoint for DynamoDB allows EC2 instances in a private subnet to access DynamoDB without traversing the internet or requiring a NAT gateway. By attaching an IAM role to the EC2 instance, the application can securely obtain temporary credentials via the instance metadata service, eliminating the need to store long-term credentials on the instance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Store AWS credentials in a file on the instance and use them in the application
Why it's wrong here
Storing AWS credentials directly in a file on an EC2 instance is a significant security risk. If the instance is compromised, these static, long-term credentials could be exfiltrated and used to access AWS resources indefinitely, leading to unauthorized access and potential data breaches. This method also complicates credential rotation and management, making it non-compliant with security best practices for production environments.
- ✗
Configure security group rules to allow outbound traffic to DynamoDB
Why it's wrong here
Configuring security group rules to allow outbound traffic is insufficient for accessing DynamoDB because security groups operate at the network layer, controlling TCP/UDP ports and IP addresses. DynamoDB is an AWS service accessed via its API endpoints over HTTPS, not through a direct network connection to a specific IP address or port range that a security group would typically manage for a database instance. While outbound internet access might be a prerequisite for reaching public API endpoints, security groups do not provide the necessary authentication or authorization for the API calls themselves.
- ✗
Attach a NAT gateway to the private subnet and use IAM user credentials
Why it's wrong here
Attaching a NAT Gateway enables instances in a private subnet to initiate outbound connections to the internet, which could include public AWS service endpoints, but it does not address authentication. Using IAM user credentials directly on an EC2 instance is insecure because these are long-term credentials designed for human users or programmatic access outside of AWS compute services. They lack the temporary, automatically rotated nature of IAM roles, posing a significant risk if compromised and requiring manual management.
- ✓
Create a VPC endpoint for DynamoDB and attach an IAM role to the instance
Why this is correct
Creating a VPC endpoint for DynamoDB establishes a private, secure connection directly from the VPC to the DynamoDB service, bypassing the public internet and enhancing data security and network performance. Concurrently, attaching an IAM role to the EC2 instance provides temporary, automatically rotated credentials that the application can assume, adhering to the principle of least privilege and eliminating the need to store static credentials on the instance. This combination offers both secure network access and robust authentication.
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Same concept, more angles
1 more way this is tested on DVA-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An application running on an EC2 instance needs to access a DynamoDB table. The instance is in a private subnet. What is the most secure way to grant access without using long-lived credentials?
hard- A.Create a VPC endpoint for DynamoDB and attach a security group to allow access.
- B.Store IAM user access keys in the application configuration file.
- ✓ C.Create an IAM role with DynamoDB access and attach it to the EC2 instance profile.
- D.Use a security group to allow the EC2 instance to communicate with DynamoDB.
Why C: It uses an IAM role attached to the EC2 instance profile, which allows the instance to obtain temporary security credentials from the AWS Security Token Service (STS). This eliminates the need for long-lived credentials and follows the principle of least privilege. The instance can securely access DynamoDB without storing any secrets on the instance.
Last reviewed: Jun 24, 2026
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