EIPs stand for Elastic IP Addresses in AWS.
An Elastic IP Address is a static, public IPv4 address designed for dynamic cloud computing. EIPs are associated with your AWS account, not specific instances or resources. This allows you to remap the IP address to a different instance in your account as needed.
Here are some key points about EIPs:
- Public IP Address: An EIP is a public IPv4 address that you can associate with an AWS resource, such as an EC2 instance or a Network Address Translation (NAT) gateway.
- Remapping: You can remap an EIP from one resource to another within the same AWS account. This allows you to mask instance failures by remapping the EIP to a new instance.
- Regional Scope: EIPs are tied to a specific AWS region and cannot be remapped across regions.
- Limited Quantity: AWS imposes a limit on the number of EIPs you can allocate per region. This limit can be increased by requesting an increase from AWS Support.
- Charges: EIPs are free if associated with a running instance. However, you are charged a small hourly fee for any unassociated EIPs.
- Use Cases: EIPs are commonly used in scenarios where a consistent public IP address is required, such as hosting web servers, running network appliances, or creating a resilient NAT gateway setup.
AWS Trusted Advisor monitors your EIP usage and service limits, providing recommendations if you are approaching the maximum allowed EIPs in a region. It can also identify any unassociated EIPs that may be incurring unnecessary charges.
Proper management of EIPs is essential for maintaining a cost-effective and secure AWS environment, especially in scenarios where a static public IP address is required.