How twtech Allocates Elastic IP Addresses from aws pool & associate them with its instances.

An Elastic IP address (EIP) in AWS is a static, public IPv4 address that twtech may allocate to AWS account. Unlike regular public IPs that change when twtech stops and start an instance, an Elastic IP stays the same until twtech choose to release it.

twtech typically uses an Elastic IP to mask the failure of an instance or software by rapidly remapping the address to another instance in twtech account.

AWS, step-by-step deploy of eip: GUI

 AWS Console Method:

1. Sign in to the AWS Management Console.
2. Go to the EC2 Dashboard.
3. In the left menu, scroll down to Network & Security and click Elastic IPs.
4. Click the Allocate Elastic IP address button.
5. Choose:
• Scope (choose "VPC" — default for most cases or twtec-custom-vpc)
• Public IPv4 Pool (usually "Amazon's pool" unless twtech have its own IPs)
6. Click Allocate.
7. After allocation, twtech will see a new Elastic IP address listed.
8. (Optional) Associate it with an EC2 instance or network interface by selecting it and clicking Associate Elastic IP address.

 AWS CLI Method:

If you prefer the command line, you can also do it using AWS CLI:

# bash 

aws ec2 allocate-address --domain vpc

It will return details like the new Elastic IP address and allocation ID.

To associate it with an instance:

#  bash

aws ec2 associate-address --instance-id i-xxxxxxxxxxxxx --allocation-id eipalloc-xxxxxxxxxxxxx

How twtech allocates an Elastic IP address(eip)  to an instance.

Go to ec2 Dashboard.

Allocate Elastic IP address from aws pool of eip addresses.

Associate or attach eip (twtech-webserver-eip) to instance(twtech-web-server)

Choose an instance to associate eip to:

How twtech Verifies that eip in now attached to instance.

How twtech disassociates eip with instances:

Confirm to disassociate eip:

Always release eip back to aws pool, else charges will still be made.

Confirm to release the eip back to aws pool:

twtech-insights:

The pricing for elastic ip in aws

As of April 2025, AWS charges $0.005 per hour for each public IPv4 address, including Elastic IP (EIP) addresses, regardless of whether they are attached to a resource or not. ​ Elastic IP Pricing Details

• In-use Elastic IPs: $0.005 per hour when associated with a running EC2 instance or other AWS resources.
• Idle Elastic IPs: $0.005 per hour when not associated with any resource.
• Additional Elastic IPs: $0.005 per hour for each additional EIP associated with a running EC2 instance beyond the first one.​

These charges apply across all AWS regions, including commercial, AWS China, and GovCloud regions. ​

 AWS Free Tier

AWS offers a Free Tier that includes 750 hours of public IPv4 address usage per month for the first 12 months after you open your AWS account.

 Cost Optimization Tips

• Release Unused EIPs: To avoid unnecessary charges, release Elastic IPs that are no longer in use.
• Monitor Usage: Utilize AWS tools like Public IP Insights and AWS Cost Explorer to monitor and manage public IP address usage effectively. ​ 

twtech Final thoughts:

Eip are paid, when twtech does not need any , it would disassociate with the instance and release back to aws pool.

• Static: It doesn’t change over time unless you release it.
• Public: It’s reachable from the internet.
• Portable: twtech can move it between EC2 instances or network interfaces.
• Charges: AWS charges twtech if it allocates an Elastic IP but don’t associate it with a running resource (like an EC2 instance). ...Yes, twtech is charged for any eip addresses once created.