IP Address in Amazon Web Service

IP address associated with EC2 Instances. Having three IP address:
Public IP address
Private IP address
Elastic IP address

Public IP Address:
It is automatically assigned when instance is started. It is assigned to EC2 instance for connectivity. If you stop or terminate instance then public IP address associated with instance is released. On Restart the Instance you get assigned a new public IP address. Public IP address can be change through life cycle of EC2 instance. You cannot use it for website or domain name registration purpose because Public IP address can be changed. To overcome this Elastic IP address is used.
Note: When you start the server or instance then may be every time new public IP address is assigned.

Private IP Address:
It is used for internal Communication between internal Server. It is not changed when you restart the Instance. It is like internal communication between Instances present at data center.

Elastic IP Address:
Elastic IP address are Static or Public IP address. By Default you have limit in AWS for 5 EIPs Per region. It is also a public address, It is issued on the basis of AWS account.It is permanently assigned to your account. You can associate and release with your instances as you wish. You can also move it from one server to other it’s good thing in Elastic IP address. you can safely fail over with help of Elastic IP address.
Note:
1. If you do not use then there is cost, if you use Elastic IP then no cost.
2. When you assigned the Elastic IP address then Public IP address gone and it is same as Elastic IP address, now we have same ip address as permanently.

ScreenShot for EC2 Instance display Private, Public and Elastic IP Address:

Associating an Elastic IP address:

Network –> Elastic IP –> Add New IP address –> Associate with Instance —> Check Instance its public or elastic IP address is same.

Create the Elastic IP address on following link: ELASTIC IP ADDRESS