The correct solution is to configure the Lambda function to run in the VPC with the appropriate security group. When a Lambda function is associated with a VPC, it can use private subnets that have routes to the virtual private gateway connected via AWS Direct Connect. The function is then able to securely communicate with resources in the on-premises network, including private databases, as long as security group and routing configurations are correct.

Why the other options are incorrect:

Setting up a VPN connection is unnecessary because Direct Connect is already in place and designed for high-throughput, low-latency, private connectivity between AWS and the on-premises data center. Adding a VPN would add cost and complexity without providing any additional benefit in this context.

Updating the VPC route tables is insufficient if the Lambda function is not running inside the VPC. Lambda functions that are not VPC-connected operate in a separate managed environment and do not honor VPC route tables. Simply adding a route will not bridge the function to the data center unless the function is explicitly VPC-attached.

Creating an Elastic IP address and trying to route Lambda traffic through it without an elastic network interface is technically invalid. Lambda functions do not support direct use of Elastic IPs and cannot send outbound traffic through them unless they are configured behind a NAT gateway or similar constructnone of which help in connecting to a private on-premises resource.

Why this question matters: This scenario tests the candidates understanding of hybrid connectivity and serverless networking. It's a common situation in enterprise environments where legacy systems need to integrate with modern, cloud-native components like Lambda.

Exam tip: When a Lambda function must access private resourceseither within AWS or on-premisesit must be configured to run inside the VPC. Once inside, security groups and routing rules determine access. Direct Connect and virtual private gateways support private traffic, but only from within the VPC infrastructure.

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