What Is an Elastic IP?

In AWS, most public IPs are temporary. Restart an EC2 instance, and it could receive a completely different IP. For basic setups, this isn’t always a problem. But if you’re running infrastructure that depends on stable connectivity—like proxies, licensed software (e.g., cPanel), or DNS entries—constantly changing IPs will break things.

Elastic IPs solve this by giving you control over a permanent IP address. You can detach it from one instance and move it to another in seconds. This flexibility ensures your service remains accessible, whether you’re scaling proxies, replacing servers, or managing failover.

While AWS provides Elastic IPs for free when attached to a running instance, there’s a small charge if they’re idle, since they’re a limited resource.

Code Example

Here’s a quick AWS CLI example of allocating and assigning an Elastic IP:

# Allocate a new Elastic IP
aws ec2 allocate-address --domain vpc

# Associate it with an instance
aws ec2 associate-address --instance-id i-0123456789abcdef0 --allocation-id eipalloc-12345678

Running proxy infrastructure

Elastic IPs provide stable entry points for proxy services. This ensures clients can consistently connect without DNS changes every time an instance restarts.

Reliable DNS pointing

If your domain points directly to an EC2 instance, an Elastic IP prevents disruptions caused by changing public IPs.

Application licensing

Many server tools, like WHM/cPanel, tie licenses to a fixed IP. Elastic IPs make sure those licenses remain valid.

Failover and redundancy

If a proxy node or server fails, you can instantly remap the Elastic IP to a backup instance—keeping traffic flowing with minimal downtime.

Use Elastic IPs only where needed

They’re ideal for proxy endpoints and public-facing services, but don’t assign them to every instance. Elastic IPs are limited per region (default: 5).

Release unused Elastic IPs

Since AWS charges for idle EIPs, make sure you release any that aren’t actively attached to running instances.

Automate remapping

In proxy fleets or scaling environments, scripts or orchestration tools (like Terraform or Ansible) can automatically reassign Elastic IPs during failover or scaling events.

Secure the endpoint

Even with a stable IP, always protect your proxy endpoints with proper firewalls and access controls to prevent abuse.

An Elastic IP is a permanent, public IPv4 address in AWS. It ensures stability across restarts and makes it easy to move traffic between instances. For anyone running proxies, hosting services, or licensing software tied to IP addresses, Elastic IPs are the simplest way to keep infrastructure reliable.