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    Elastic IP Address:FAQ about features and limitations

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    Elastic IP Address:FAQ about features and limitations

    Last Updated:Nov 21, 2025

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

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

    Resources within a VPC rely on public IP addresses to communicate with the internet over IPv4. Public IPv4 addresses are categorized into two types: static public IP addresses and EIPs.

    A static public IP address can only be assigned to a resource, such as an ECS instance or an SLB instance, at creation. It cannot be disassociated or re-associated after creation and is released only when you delete the instance. In contrast, an EIP is an independent public IP resource that you can create, hold, and dynamically manage. We recommend using EIPs for flexible IP management.

    How do I determine whether an ECS instance is associated with a static public IP address or an EIP?

    Log on to the ECS console, click the ID of the ECS instance that you want to manage, and then view the public IP address associated with the ECS instance.

    View the values of the Public IP Address and EIP parameters:

    • Public IP Address: If an IP address is displayed, the ECS instance is associated with a static public IP address.

    • EIP: If an EIP address is displayed, the ECS instance is associated with an EIP.

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    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.

    Does an EIP automatically change?

    No, an EIP does not automatically change.

    If an EIP expires or the payment is overdue, the EIP may be released. You can apply for a specific EIP to retrieve a released EIP.

    If an ECS instance is assigned a public IP address, the public IP address is released in the following scenarios: the ECS instance is released, the bandwidth of the ECS instance is set to 0, or you stop the ECS instance and select Economical Mode. When you re-assign a public IP address to the ECS instance, a different IP address may be used.
    If you want to assign a public IP address to another ECS instance or retain a public IP address after an ECS instance is released, we recommend that you use EIPs. Compared with public IP addresses, EIPs are more flexible. You can associate EIPs with and disassociate EIPs from ECS instances as needed. You can also convert public IP addresses to EIPs.