Which solution meets these requirements?
Create a NAT gateway in the private subnet. Create a route table entry from the private subnet to the internet gateway.
Create a NAT gateway in a public subnet. Create a route table entry from the private subnet to the NAT gateway.
Launch a NAT instance in the private subnet. Create a route table entry from the private subnet to the internet gateway.
Launch a NAT instance in a public subnet. Create a route table entry from the private subnet to the NAT instance.
Explanations:
A NAT gateway must be in a public subnet to provide internet access. Placing it in the private subnet does not work.
A NAT gateway in a public subnet allows instances in the private subnet to access the internet, while restricting inbound traffic from the internet.
A NAT instance in the private subnet cannot route traffic to the internet as the private subnet has no direct route to the internet gateway.
While a NAT instance in a public subnet can route traffic, it is not as scalable or highly available as a NAT gateway. Additionally, managing a NAT instance requires more effort.
I would say the answer is:
Create a NAT gateway in a public subnet. Create a route table entry from the private subnet to the NAT gateway.