A new VPC with CIDR range 10.10.0.0/16 has been set up with a public and a private subnet. Internet Gateway and a custom route table have been created, and a route has been added with the `Destination` as `0.0.0.0/0` and the `Target` with Internet Gateway ( igw-id ). A new Linux EC2 instance has been launched on the public subnet with the auto-assign public IP option enabled, but the connection is getting failed when trying to SSH into the machine. What could be the reason?

Answer options:

A.Elastic IP is not assigned.
B.The NACL of the public subnet disallows the ingress SSH traffic.
C.A public IP address is not assigned.
D.The Security group of the instance disallows the egress traffic on port 80.

Answer: B
Option A is incorrect. An Elastic IP address is a public IPv4 address with which you can mask the failure of an instance or software by rapidly remapping the address to another instance in your account.
If your instance does not have a public IPv4 address, you can associate an Elastic IP address with your instance to enable communication with the internet; for example, to connect to your instance from your local computer.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/elastic-ip-addresses-eip.html#eip- basics
From our problem statement, EC2 is launched with Auto-assign public IP enabled. So, since public IP is available, Elastic IP is not necessary to connect from the internet.
Option C is incorrect because the problem statement clearly states that EC2 is launched with Auto-assign Public IP enabled, so this option cannot be true.
Option B is CORRECT as the NCL may not allow the ingress SSH traffic so that the connection failed to connect.
Option D is incorrect because SSH uses port 22. A security group is stateful and in this scenario, the security group may disallow the ingress SSH traffic instead of egress.