The ec2 instance can't access internet in a public subnet without a elastic ip address?

Question

I working on aws. I created a public subnet which has a network ACL allows all net traffic, and associated with a internet gateway in the route table.

And then I create

Answer 1

As well as being in a subnet that has a route to an Internet gateway, an instance must have a public IP address to communicate with the outside world (this is distinct from an elastic IP).

You can specify this when launching an instance, if not there is a per subnet setting that controls this. The per subnet setting defaults to false other than default subnets in your default VPC. There are more details in the aws docs.