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    Server Load Balancer:Create and manage CLB instances

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    Server Load Balancer:Create and manage CLB instances

    Last Updated:Jun 02, 2026

    Classic Load Balancer (CLB) distributes client requests across backend servers at Layer 4 and Layer 7, eliminating single points of failure and improving application availability and stability.

    Internal access

    An internal CLB instance receives a private IP address within its VPC. Clients with connectivity to the VPC can access your service through this IP address.

    Console

    Go to the CLB buy page, complete the following configurations, and then click Create Now.

    • Region: Select the region where your backend servers are deployed.

    • Zone Type:

      • If a region supports multiple availability zones, Multi-zone is selected by default and cannot be changed. The instance deploys across primary and secondary availability zones for automatic failover.

      • In regions with only one availability zone, only Single-zone is supported.

    • Primary Zone: Select the availability zone that serves traffic. Fixed after creation — to change, create a new instance.

    • Instance Type: Select Intranet to allocate a private IP from the specified vSwitch CIDR block.

    • Instance Billing Method: Pay-By-LCU.

      Effective 00:00:00 (UTC+8) on June 1, 2025, Alibaba Cloud will stop selling CLB instances that are billed by specification.

    • IP Version: Only IPv4 is supported.

    • VPCId and VswitchId: Select the VPC and vSwitch in the region and primary availability zone for the CLB instance.

    • Internal instances do not incur data transfer fees. After creation, you can bind an EIP to the instance to enable Internet access. The EIP provides Internet access and incurs data transfer fees.

    • Instance Name, Tags, and Resource Group: Specify these to simplify management. After purchase, you can modify the instance name and configure tags on the details page.

    API

    Call CreateLoadBalancer and set AddressType to intranet to create an internal CLB instance.

    Internet access

    • Internet-facing CLB instance: The system assigns a static public IP address bound to the instance for Internet access.

      When you release an Internet-facing IPv4 CLB instance, you can choose to convert the static public IP address into an EIP and retain it.
      Static public IP addresses cannot be added to an Internet Shared Bandwidth instance.

    • Bind an EIP to an internal CLB instance (Recommended): An EIP provides Internet access and can be flexibly bound or unbound. You can add EIPs to an Internet Shared Bandwidth instance to reduce data transfer costs.

    Create an Internet-facing CLB instance

    Console

    Go to the CLB buy page, complete the following configurations, and then click Create Now.

    API

    Call CreateLoadBalancer and set AddressType to internet to create an Internet-facing CLB instance.

    Bind an EIP to an internal CLB

    • An intranet CLB instance can be bound to only one EIP in the same region.

    • After you bind an EIP, the EIP incurs fees.

    Console

    1. Go to the CLB buy page and create an intranet CLB instance. Create an intranet CLB instance.

    2. In the Actions column of the target internal CLB instance, choose More > Change Specification > Bind EIP.

      Select an available EIP. If no EIPs are available, click Purchase EIP and follow the on-screen instructions to create one.

    API

    1. Call CreateLoadBalancer and set AddressType to intranet to create an internal CLB instance.

    2. Call AssociateEipAddress to bind an EIP.

    Configuration protection

    Enable deletion protection and configuration read-only mode to prevent accidental deletion or modification.

    Configuration read-only mode applies only to the CLB console. You can still modify configurations through API operations.

    Console

    Go to the Instances page of the CLB console, click the ID of the target instance to go to the Instance Details page. In the Basic Information section, turn on or turn off the Deletion Protection and Configuration Read-only Mode switches.

    API

    Idle instances

    Release idle instances promptly to better manage costs.

    • A pay-as-you-go CLB instance is idle if it has not been used for more than 7 consecutive days and meets any of the following conditions:

      • The instance is in the Stopped state.

      • No listeners are configured for the instance.

      • All listeners of the instance are stopped.

      • No backend servers are added to the instance.

      • The weights of all backend servers of the instance are set to 0.

    • Idle instances still incur fees. A CLB instance incurs fees until it is released.

    Console

    1. Go to the Idle Instances page of the CLB console to view pay-as-you-go instances unused for more than seven days.

    2. In the upper-right corner of the idle instance list, click Settings to customize displayed columns, such as IP Address, Region, and Cause of Idleness.

    3. Confirm the instance is not in use and no longer needed, then click Release in the Actions column.

    Resource cleanup

    • Prerequisites

      • You cannot release an instance for which deletion protection is enabled. You must first go to the Instance Details page and turn off the Deletion Protection switch.

      • You can release only pay-as-you-go instances.

    • Release methods

      • You can select Release Now or Scheduled Release based on your business requirements. If you select scheduled release, the system stops billing at the specified time and releases the instance at the next hour.

      • Internet-facing IPv4 CLB instances: When you release an instance, you can choose whether to convert its public IP address to an EIP and retain the EIP.

        • You can bind a retained EIP to other instances in the same region. This allows you to use the same public IP address when you migrate instances.

          When you perform this operation for the first time, the system automatically creates a service-linked role named AliyunServiceRoleForSlbEipAccess to allow CLB to access EIPs.

        • A retained EIP is billed separately. By default, the EIP is a pay-as-you-go resource that is billed based on data transfer. The default maximum bandwidth is 200 Mbit/s.

    • Impacts

      • After a CLB instance is released, its configurations and data are deleted and cannot be restored.

      • Releasing a CLB instance does not affect running backend servers.

      Warning

      • If you mapped a custom domain name to the IP address of a CLB instance, change the DNS record to point to another load balancer instance before you release the CLB instance to prevent service interruptions.

      • After a CLB instance is released, all configurations and data associated with the instance will be deleted and cannot be recovered.

      • If your CLB instance is managed by another Alibaba Cloud service such as Container Service for Kubernetes (ACK), releasing the CLB instance will disrupt the related service. This action is irreversible.

    Console

    1. Go to the Instances page of the CLB console. In the Actions column of the target instance, choose More Actions > Release Settings.

    2. Select a Release. When you release an Internet-facing IPv4 CLB instance, you can select Convert to EIP and Retain the IP.

    API

    Call the DeleteLoadBalancer operation to release a pay-as-you-go CLB instance.

    Billing

    Newly purchased CLB instances support only the pay-as-you-go billing method.

    Effective 00:00:00 (UTC+8) on June 1, 2025, Alibaba Cloud will stop selling CLB instances that are billed by specification.

    • Internet-facing CLB instance: Fees include instance fees, public IP retention fees, LCU fees, and data transfer fees.

    • Internal CLB instance: Fees include instance fees and LCU fees. If you bind an EIP, the EIP is billed separately.

    Quotas

    Resource

    Default quota

    Increase quota

    CLB instances per Alibaba Cloud account

    30

    To increase this quota:

    Related topics

    • Server groups: Groups of backend servers that receive requests from a CLB instance.

    • Listeners: Check for connection requests and distribute them to backend servers based on the configured scheduling algorithm.

    • Configure a domain name: Map a custom domain name to the CLB service IP address so clients can access services through the domain name.