You have created a NAT gateway to ensure that instances in your private subnet can download updates from the internet. But the instances are still not able to reach the internet even after the gateway has been created. Which of the following could be one of the underlying issues?

Answer options:

A.The NAT gateway has not been created with the wrong AMI.
B.The NAT gateway has been created in the public subnet.
C.The NAT gateway has been created with the wrong Instance type.
D.The NAT gateway has been created in the private subnet.

Answer – D
Options A and C are incorrect because this is relevant when you are creating NAT Instances.
Option B is incorrect since the NAT gateway should be created in the public subnet.
The AWS Documentation mentions the following.
To troubleshoot instances that can’t connect to the Internet from a private subnet using a NAT gateway, check the following.
Verify that the destination is reachable by pinging the destination from another source using a public IP address.
Verify that the NAT gateway is in the Available state. Note: A NAT gateway in the Failed state is automatically deleted after about an hour.
Make sure that you`ve created your NAT gateway in a public subnet and that the public route table has a default route pointing to an Internet gateway.
Make sure that the private subnet’s route table has a default route pointing to the NAT gateway.
Check that you have allowed the required protocols and ports for outbound traffic to the Internet.
For more information on NAT gateways, please refer to the below URL
https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc-nat-gateway.html