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.
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Region and Zone: Fixed after creation. To change, create a new instance.
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Region: Select the region where your backend servers are deployed.
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Availability Zone: Select the primary availability zone that serves traffic.
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Zone Type:
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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.
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In regions with only one availability zone, only Single-zone is supported.
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InstanceChargeType: PayByCLCU.
Effective 00:00:00 (UTC+8) on January 1, 2026, Alibaba Cloud will stop selling CLB instances that are billed by specification.
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Instance Type: Select Internal Network to allocate a private IP from the specified vSwitch CIDR block.
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VPC: Select the VPC and vSwitch in the region and primary availability zone for the CLB instance.
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IP Version: Only IPv4 is supported.
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Internet Data Transfer Fee: 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.
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Instance Name, Tag, 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
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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.
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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.
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Instance Type: Select Internet. The system assigns a static public IP address to the instance.
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IP Version: Supports IPv4 and IPv6.
Regions that support IPv6 CLB instances.
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Internet Data Transfer Fee: By traffic.
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Other configurations follow Create an internal CLB instance.
API
Call CreateLoadBalancer and set AddressType to internet to create an Internet-facing CLB instance.
Bind an EIP to an internal CLB
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You can bind an EIP or an Anycast EIP to an internal CLB instance.
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An intranet CLB instance can be bound to only one EIP or Anycast EIP:
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To bind an EIP, the intranet CLB instance and the EIP must be in the same region.
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Only CLB instances in the following regions support binding an Anycast EIP.
Area
Region
Asia Pacific - China
China (Hong Kong)
Asia Pacific - Other
Philippines (Manila), Japan (Tokyo), Singapore, Malaysia (Kuala Lumpur), Indonesia (Jakarta), South Korea (Seoul), Thailand (Bangkok)
Europe and the Americas
US (Silicon Valley), US (Virginia), Germany (Frankfurt), UK (London)
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After you bind an EIP or Anycast EIP, the IP address incurs fees.
Console
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Go to the CLB buy page and create an intranet CLB instance. Create an intranet CLB instance.
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In the Actions column of the target internal CLB instance, choose
> Change Specification > Bind EIP.-
IP Type: Select EIP or Anycast EIP.
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IP Address: Select an available EIP or Anycast EIP. If no IP addresses are available, click Purchase EIP or Purchase Anycast EIP and follow the on-screen instructions to purchase one.
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API
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Call CreateLoadBalancer and set
AddressTypetointranetto create an internal CLB instance. -
Call AssociateEipAddress to bind an EIP, or call AssociateAnycastEipAddress and set
BindInstanceTypetoSlbInstanceto bind an Anycast 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
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Call SetLoadBalancerDeleteProtection and set
DeleteProtectionto enable or disable deletion protection. -
Call SetLoadBalancerModificationProtection and set
ModificationProtectionStatusto enable or disable configuration read-only mode.
Idle instances
Release idle instances promptly to better manage costs.
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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:
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The instance is in the Stopped state.
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No listeners are configured for the instance.
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All listeners of the instance are stopped.
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No backend servers are added to the instance.
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The weights of all backend servers of the instance are set to 0.
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Idle instances still incur fees. A CLB instance incurs fees until it is released.
Console
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Go to the Idle Instances page of the CLB console to view pay-as-you-go instances unused for more than seven days.
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In the upper-right corner of the idle instance list, click
to customize displayed columns, such as IP Address, Region, and Cause of Idleness. -
Confirm the instance is not in use and no longer needed, then click Release in the Actions column.
Resource cleanup
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Prerequisites
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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.
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You can release only pay-as-you-go instances.
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Subscription instances: These instances are automatically released upon expiration and cannot be manually released. If required, go to the Unsubscribe management center to request a self-service unsubscription.
Subscription CLB instances are no longer available for purchase since December 1, 2024. Renewals will be discontinued starting December 1, 2026. Before your renewal expires, you can choose to renew or switch to the pay-as-you-go billing method. For more information, see End of sale for CLB subscription instances.
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Release methods
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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.
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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.
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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.
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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.
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Impacts
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After a CLB instance is released, its configurations and data are deleted and cannot be restored.
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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.
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After a CLB instance is released, all configurations and data associated with the instance will be deleted and cannot be recovered.
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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.
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Console
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Go to the Instances page of the CLB console. In the Actions column of the target instance, choose
> Release Settings. -
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 January 1, 2026, Alibaba Cloud will stop selling CLB instances that are billed by specification.
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Internet-facing CLB instance: Fees include instance fees, public IP retention fees, LCU fees, and data transfer fees.
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Internal CLB instance: Fees include instance fees and LCU fees. If you bind an EIP, the EIP is billed separately.
Quotas
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Resource |
Default quota |
Increase quota |
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CLB instances per Alibaba Cloud account |
60 |
To increase this quota:
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Related topics
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Server groups: Groups of backend servers that receive requests from a CLB instance.
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Listeners: Check for connection requests and distribute them to backend servers based on the configured scheduling algorithm.
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Configure a domain name: Map a custom domain name to the CLB service IP address so clients can access services through the domain name.