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 (Single Public Subnet)

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

Step by step :

1. Create VPC with CIDR (ex : 172.31.0.0/16)
2. Create subnet (ex : 172.31.1.0/24)
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 (with NAT Gateway)

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.

Step by step :

1. Create VPC with cidr (ex : 172.31.0.0/16)
2. Create subnet 1 (ex : 172.31.1.0/24)
3. Create subnet 2 (ex : 172.31.2.0/24)
4. Create internet gateway (attach to the VPC)
5. Create nat gateway (with public ip, and with private ip in public subnet, 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

   172.31.1.0/24

7. 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

   172.31.2.0/24

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