AWS Certified Advanced Networking – Specialty (ANS-C00) — Question 70

A company has an application running on Amazon EC2 instances in a private subnet that connects to a third-party service provider's public HTTP endpoint through a NAT gateway. As request rates increase, new connections are starting to fail. At the same time, the ErrorPortAllocation Amazon CloudWatch metric count for the NAT gateway is increasing.
Which of the following actions should improve the connectivity issues? (Choose two.)

Answer options

• A. Allocate additional Elastic IP addresses to the NAT gateway.
• B. Request that the third-party service provider implement HTTP keepalive.
• C. Implement TCP keepalive on the client instances.
• D. Create additional NAT gateways and update the private subnet route table to introduce the new NAT gateways.
• E. Create additional NAT gateways in the public subnet and split client instances into multiple private subnets, each with a route to a different NAT gateway.

Correct answer: C, D

Explanation

Implementing TCP keepalive on the client instances (Option C) helps maintain the connection by allowing idle connections to stay open longer, which reduces the chance of connection failures. Creating additional NAT gateways (Option D) balances the load and prevents port exhaustion, thereby addressing the increasing ErrorPortAllocation metric. The other options do not directly resolve the connectivity issues as effectively.