Create New VPC Environment in AWS

Purpose

Amazon Virtual Private Cloud (Amazon VPC) enables us to launch AWS resources into a virtual network that we've defined.
This virtual network closely resembles a traditional network that we'd operate in our own data center, with the benefits of using the scalable infrastructure of AWS.

Create AWS VPC with Public Subnet Only

This VPC make all instances must use public ip (elastic) to get access to internet and to be able to accessed from internet.

1. Create VPC with CIDR (ex : 172.31.0.0/16)
2. Create subnet (ex : 172.31.156.0/24)
3. Create internet gateway (attach to the VPC)
4. Edit route tables (which already attached to the VPC automatically)

 :  Route
     :: destination : 172.31.0.0/16 ; target : local
     :: destination : 0.0.0.0/0 ; target : internet gateway

Note : In this VPC, we don't need to create new route tables. Just need to edit.

Create AWS VPC with Public & Private Subnet

This VPC must be created with two subnets.
One as public subnet, where all instances in this subnet must use public ip (elastic ip) to get access to internet and to be able to accessed from internet.
The second one as private subnet, where all instance only use private ip. They can access internet through a NAT gateway. But they can not be accessed directy from internet.

1. Create VPC with cidr (ex : 172.31.0.0/16)
2. Create subnet 1 (ex : 172.31.156.0/24)
3. Create subnet 2 (ex : 172.31.157.0/24)
4. Create internet gateway (attach to the VPC)
5. Create nat gateway (with public ip, attach to the VPC)
6. Create route tables 1 (attach to the vpc)

 #: Route 
    #:: Destination : 172.31.0.0/16 ; target : local
    #:: Destination : 0.0.0.0/0 ; target : internet gateway
 #: Subnet Association
    #:: 172.31.156.0/24

1. Create route tables 2 (attach to the VPC)

 #: Route 
    #:: Destination : 172.31.0.0/16 ; target : local
    #:: Destination : 0.0.0.0/0 ; target : nat gateway
 #: Subnet association
    #:: 172.31.157.0/24

Note : In this VPC, just keep the existing route table and then we need to create new two route tables.