Elastic IP, Static IP, Public IP. What’s the Difference?

4 min readDec 23, 2016


AWS network infrastructure can become complex.

Between integrating a content delivery network (CDN), network optimizer, or dynamic content accelerators, structuring VPCs and instances takes strategic planning.

Within AWS, having Elastic IPs can simplify your infrastructure and make making adjustments easier. With Elastic IPs, your changing environments and business requirements mean you need a way to easily adjust your setup.

That is why knowing what is an Elastic IP, and what are static and public IPs, can help make better decisions in designing your AWS setup.

What is an Elastic IP?

Elastic IP addresses are used by AWS to manage its dynamic cloud computing services. Within the AWS infrastructure, customers have virtual private clouds (VPCs). Within the VPCs, users have instances. The Elastic IP address is what is used to advertise the data within the instance to the public internet.

If the discussion ended there, you would assume there isn’t much difference between a public IP address and an elastic IP address. That is why we need a bit more explaining about what an Elastic IP address is for.

Within the AWS cloud environment, AWS states that the Elastic IP is used for dynamic cloud computing. The distinction here is important. If an instance goes down within AWS, you want to maintain your IP address, as well as maintain communication with your AWS account.

Thus, an Elastic IP is a combination of a public IP address and a static IP address. It allows you to continue to advertise AWS instances within your AWS network infrastructure.

But, to fully understand the elastic IP, we should understand static IP addresses and public IP addresses.

What is a Static IP?

Your internet service provider (ISP) provides you an IP address. This advertises your computer to the internet.

An IP address is like your home postal address, which is a piece in a larger city block. A city block, in internet language, is a network prefix. To go one step further, network prefixes are part of autonomous systems (AS). When connecting people to the internet, ISPs will assign an IP address to your computer.

The IP address that is assigned to you is most likely a dynamic IP address. This is the most common for residential customers. This means that the IP address changes frequently, which provides customers and ISPs cost savings. In the case of Germany, Deutsche Telekom is typically changing IP addresses every day.

The alternative to this system is the static IP address. This is an IP address that never changes. If you are running a dynamic cloud environment, this would be necessary for advertising your content to the public internet. This is a primary function of AWS Elastic IPs, which contain the static IP address component.

A static IP is useful for various reasons. In cloud computing, a static IP address is advantageous for DNS queries. If IPs are changing, this can affect the content loading process.

Static IP addresses are IPs which do not change. They are common for business and cloud computing, which is why AWS includes this within the Elastic IP framework.

Understanding Public IP Addresses

A Public IP address is how the internet identifies you. A public IP address is the IP address that communicates your internet connected device to the public internet.

There is the ability to have a public IP address or a private IP address. A private IP address is for a private network. These are less common, and with your AWS infrastructure, not going to be in your interest when discussing Elastic IPs.

An Elastic IP has the public IP address component, as you need to advertise your AWS instances to the public internet. As the AWS Elastic IP will advertise a public, static IP address that can compensate for fluctuations in your AWS infrastructure, they are necessary in dynamic cloud computing.

The Public, Static, and Elastic IP Debate

The debate between what IP address is right for your business comes down to necessity.

What are you trying to accomplish?

We have said this in a few other networking posts, and the common thought for network design is: “it depends”.

Having an understanding of the different IP address structures available to you can help you make better decisions.

With your AWS Elastic IP address, you have all the requirements for dynamic cloud computing.




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