This topic provides answers to some commonly asked questions about elastic IP addresses (EIPs).

What is an EIP?

An EIP is a public IP address that you can purchase and hold as an independent resource. You can associate EIPs with Elastic Compute Service (ECS) instances, internal Server Load Balancer (SLB) instances, secondary elastic network interfaces (ENIs), NAT gateways, and high-availability virtual IP addresses (HAVIPs). The ECS instances, internal SLB instances, and secondary ENIs must be deployed in virtual private clouds (VPCs).

An EIP is also a type of Network Address Translation (NAT) IP address that is deployed in the public-facing gateway of Alibaba Cloud, and is mapped to the associated cloud resource through NAT. After an EIP is associated with a cloud resource, the cloud resource can access the Internet through the EIP.

What are the benefits of EIPs?

EIPs have the following benefits:
  • Independently purchased and owned

    You can purchase and hold an EIP as an independent resource. You do not need to purchase it together with other computing or storage resources.

  • Flexible association

    You can associate an EIP with a cloud resource or disassociate the EIP from the cloud resource as required.

  • Adjustable bandwidth

    You can adjust the bandwidth of an EIP at any time. The new bandwidth immediately takes effect.

What are the differences between an EIP and an ECS public IP address?

The following table lists the differences between an EIP and an ECS public IP address.
Feature EIP ECS public IP address
Supported networks VPCs VPCs and classic networks
Whether you can independently hold the IP address Supported Not supported
Whether the IP address can be associated with and disassociated from an ECS instance as required Supported Not supported
Whether you can view the IP address on the ENI of the ECS instance You can view the IP address on the ENI in Cut-Through Mode or Multi-EIP to ENI Mode

Classic networks: Yes

VPCs: No

How many EIPs can I create under one Alibaba Cloud account?

You can create at most 20 EIPs under one Alibaba Cloud account. To create more EIPs, apply for a quota increase. For more information, see Quota management.

Is the number of EIP operations that I can call limited?

If you call EIP operations more than 500 times within one day, the system will respond to your requests at a lower speed.