AWS Certified Solutions Architect – Professional — Question 895

A company has developed a new billing application that will be released in two weeks. Developers are testing the application running on 10 EC2 instances managed by an Auto Scaling group in subnet 172.31.0.0/24 within VPC A with CIDR block 172.31.0.0/16. The Developers noticed connection timeout errors in the application logs while connecting to an Oracle database running on an Amazon EC2 instance in the same region within VPC B with CIDR block 172.50.0.0/16.
The IP of the database instance is hard-coded in the application instances.
Which recommendations should a Solutions Architect present to the Developers to solve the problem in a secure way with minimal maintenance and overhead?

Answer options

• A. Disable the SrcDestCheck attribute for all instances running the application and Oracle Database. Change the default route of VPC A to point ENI of the Oracle Database that has an IP address assigned within the range of 172.50.0.0/16
• B. Create and attach internet gateways for both VPCs. Configure default routes to the internet gateways for both VPCs. Assign an Elastic IP for each Amazon EC2 instance in VPC A
• C. Create a VPC peering connection between the two VPCs and add a route to the routing table of VPC A that points to the IP address range of 172.50.0.0/16
• D. Create an additional Amazon EC2 instance for each VPC as a customer gateway; create one virtual private gateway (VGW) for each VPC, configure an end- to-end VPC, and advertise the routes for 172.50.0.0/16

Correct answer: C

Explanation

Establishing a VPC peering connection is the most secure, cost-effective, and low-maintenance method to route traffic between two VPCs in the same region. Option C is correct because it allows private IP-to-IP communication over the AWS backbone network without exposing resources to the public internet. Other options like Option B introduce security risks by routing traffic over the public internet, while Option D introduces unnecessary architectural complexity and maintenance overhead.