How can the instances in the private subnet connect to the internet?
The private subnet can never connect to the internet
Use NAT with an elastic IP
Use the internet gateway with a private IP
Allow outbound traffic in the security group for port 80 to allow internet updates
Explanations:
A private subnet can connect to the internet indirectly using a NAT device, allowing it to initiate outbound connections. However, it cannot receive inbound traffic from the internet directly.
Using a NAT (Network Address Translation) gateway or instance with an Elastic IP allows instances in the private subnet to connect to the internet for updates. The NAT device translates the private IP addresses to the Elastic IP for outgoing traffic.
An internet gateway allows instances in a public subnet to connect to the internet, but it cannot be used by instances in a private subnet because they do not have public IP addresses.
Allowing outbound traffic in the security group for port 80 does not enable internet access by itself. Instances in the private subnet still require a NAT gateway or instance to facilitate outbound internet connections.
I structure that the answer is:
Use NAT with an elastic IP