What is Elastic IP address in EC2?
AWS designed static IPv4 address for dynamic cloud computing known as Elastic IP address. These IPs are associated with your AWS account and enable you to mask the failure of an instance or software by remapping the address to another instance present in your account.
An Elastic IP address is a public IPv4 address, that is accessible from the internet. If your instance is not able to communicate over the internet, you can associate an Elastic IPv4 address to it.
NOTE: Currently AWS does not support Elastic IP address for IPv4.
Why do you need to keep tabs on Elastic IP (EIP) address?
AWS grants you one Elastic IP address, which you can associate with a running instance at no charge. However, you’ll be charged for every extra EIP that you associate with an instance on an hourly basis. For the efficient use of Elastic IP addresses, AWS charges a small hourly fee when these IP addresses are not associated with any running instance or associated with a stopped instance or unattached network interface.
For example – You may stop your instance and assume that IP associated has been released with the instance. But this is not the case. Your AWS bills can prove it.
How does Centilytics assist you?
Centilytics provides a dedicated insight regarding this and gives warnings to the user whenever an unused elastic IP is detected in their infrastructure.
Insight descriptions:
| Severity | Description |
 WARNING |
This indication will be displayed when an elastic IP is not associated with an EC2 instance or a NAT gateway in your cloud infrastructure. |
Description of further columns are as follows:
- Account Id: This column shows the respective account ID of the user’s account.
- Account Name: This column shows the Account Id of the user’s account.
- Region: This column shows the region in which the resources exist.
- Identifier: This column shows the name of your elastic IP.
- Public IP: This column shows the IP address of your elastic IP.
- Potential monthly savings: This column shows the monthly saving that can be done if the unused elastic IP is deleted.
Filters applicable:
| Filter Name | Description |
| Account Id | Applying account Id filter will display all the public snapshots for the selected account Id. |
| Region | Applying the region filter will display all the public snapshots corresponding to the selected region. |
| Severity | Applying severity filter will display public snapshots according to the selected severity type i.e. selecting critical will display all instances with critical severity. Same will be the case for Warning and Ok severity types. |
| Resource Tags | Applying resource tags filter will display those public snapshots which have been assigned the selected resource tag. For e.g., If a user has tagged some public snapshots by a resource tag named environment, then selecting an environment from the resource tags filter will display all those snapshots. |
| Resource Tags Value | Applying resource tags value filter will display data which will have the selected resource tag value. For e.g. – Let’s say a user has tagged some resource by a tag named environment and has a value say production (environment: production). Hence, the user can view data of all the resources which are tagged as “environment: production”. The user can use the tag value filter only when a tag name has been provided. |
Compliances covered:
| Compliance Name | Reference No. | Link |
| Trusted Advisor | – | https://console.aws.amazon.com/trustedadvisor/home?#/category/cost-optimizing |