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    Elastic IP Address:FAQ on features, benefits, and limits

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    Elastic IP Address:FAQ on features, benefits, and limits

    Last Updated:Nov 21, 2024

    This topic provides answers to some frequently asked questions about the features, benefits, and limits of elastic IP addresses (EIPs).

    What is an EIP?

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

    EIPs are NAT IP addresses deployed on the Internet-facing gateway of Alibaba Cloud, and are mapped to the associated cloud resources through NAT. After EIPs are associated with cloud resources, the cloud resources can use the EIPs to communicate with the Internet.

    What are the benefits of EIPs?

    EIPs provide the following benefits:

    • Independent purchase and use

      An EIP can be an independent resource within your Alibaba Cloud account. You do not need to purchase EIPs with other computing resources or storage resources.

    • Flexible association and disassociation

      You can associate EIPs with resources and disassociate EIPs from resources anytime. This helps you reduce costs.

    • Flexible bandwidth adjustment

      You can adjust the maximum bandwidth of an EIP based on business requirements. Bandwidth modifications immediately take effect.

    • Flexible billing and low costs

      Multiple billing methods are supported, including subscription and pay-as-you-go (pay-by-bandwidth and pay-by-data-transfer). You can reduce bandwidth costs by associating an EIP with an Internet Shared Bandwidth instance.

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

    The following table describes the differences between an EIP and the static public IP address of an ECS instance.

    Item

    EIP

    ECS static public IP address

    Supported networks

    VPC

    VPC and classic network

    Use as an independent resource

    Supported

    Unsupported

    Associate with and disassociate from an ECS instance at any time

    Supported

    Unsupported

    How many EIPs can I apply for with an Alibaba Cloud account?

    You can apply for at most 20 EIPs with an Alibaba Cloud account. To apply for more EIPs, request a quota increase. For more information, see Manage EIP quotas.

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

    Yes. You can call EIP operations at most 500 times within one day. Subsequent API calls that are sent within the day are throttled.

    Can I resolve the domain name of a website to an EIP?

    Yes. You can create a DNS record to resolve a domain name to an EIP or a private IP address. For more information, see Add an A record for a website domain name.

    Why am I unable to modify the description of an EIP?

    In most cases, you can modify the description of an EIP on the details page. However, you cannot modify the description if an EIP is hosted by a third party. For example, you cannot modify the description of an EIP that is automatically created by the system when you create an Internet-facing Network Load Balancer (NLB) instance.

    Can I convert a BGP (Multi-ISP) EIP to a BGP (Multi-ISP) Pro EIP?

    No, you cannot convert a BGP (Multi-ISP) EIP to a BGP (Multi-ISP) Pro EIP.

    You can specify the line type only when you create an EIP. You cannot change the line type after an EIP is created.

    How do I change the public IP address of an ECS instance?

    Public IP address type

    Description

    Change an EIP

    1. (Optional) Apply for a new EIP.

      For more information, see Apply for an EIP.

    2. Disassociate the current EIP from the ECS instance.

      For more information, see Disassociate an EIP from a cloud resource.

      Important

      • After you disassociate a pay-as-you-go EIP from a cloud resource, you are still charged an EIP configuration fee. To avoid unnecessary fees, release the EIP.

      • If you no longer require a subscription EIP after you disassociate the EIP from a cloud resource, you can unsubscribe from the EIP. For more information, see Rules for unsubscribing from resources.

    3. Associate the new EIP with the ECS instance.

      For more information, see Associate an EIP with an ECS instance.

    Change the public IP address of an ECS instance

    • You can change the public IPv4 address of an ECS instance within 6 hours after the instance is created.

    • Six hours after the ECS instance is created, you must convert the public IP address to an EIP, disassociate the EIP from the ECS instance, and then assign a new public IP address by adjusting the Internet bandwidth of the ECS instance to a value greater than 1 Mbit /s.

    For more information, see Change the public IP address of an ECS instance.