A company has set up its application in AWS. It consists of a web tier hosted on a set of EC2 Instances. These instances interact with a MongoDB database server located in a private subnet. The web tier also interacts with many service-based applications in the private subnet. A NAT Instance is being used to route traffic from the instances in the private subnet to the Internet. The IT Administrative team is now getting Cloudwatch alerts that the NAT Instance is going beyond its threshold value for Network Activity. Which of the following would you advise to increase the performance of this architecture?

Answer options:

A.Place the database server and application servers in the public subnet.
B.Place the NAT instance closer to the database servers by placing them in the private subnet.
C.Use the NAT gateway service instead of the NAT Instance.
D.Use a VPN connection for the Instances in the private subnet.

Answer – C
The below snapshot from the AWS Documentation shows a partial comparison of the NAT Instance and NAT Gateway. You should consider using the NAT gateway for higher bandwidth requirements.
Option A is incorrect since you should not change the database or application servers` architecture since this would result in security issues.
Option B is incorrect since this would still alleviate the current network issue.
Option D is incorrect since the NAT instance should be used to route traffic to the Internet from the Instances in the private subnet.
For more information on the comparison between NAT Instances and the NAT gateway, please refer to the below URL-
https://docs.aws.amazon.com/vpc/latest/userguide/vpc-nat-comparison.html