This topic describes the regions and zones that support Classic Load Balancer (CLB).

Regions and zones

A region is a group of Alibaba Cloud data centers deployed within a geographical location. After you create a resource, you cannot change the region to which the resource belongs. Each region consists of one or more zones with independent power supplies and network infrastructure. If one of the zones in a region is down, another zone takes over to serve your workloads. Regions are independent of each other. Zones are isolated from each other. Connections between zones within the same region provide low network latency.

You can call the DescribeRegions and DescribeZones operations to query the regions and zones that support CLB.

Classic Load Balancer (CLB) supports cross-zone deployment in most regions. You can deploy a CLB instance across zones within the same region to achieve zone-disaster recovery and improve service stability and reliability. When the primary zone is down, Classic Load Balancer (CLB) fails over to the secondary zone within about 30 seconds. When the primary zone recovers, Classic Load Balancer (CLB) automatically fails back to the primary zone.

Before you deploy a Classic Load Balancer (CLB) instance across zones, take note of the following items:

  • Elastic Compute Service (ECS) instances added to a Classic Load Balancer (CLB) instance are deployed across the primary and secondary zones. Before you add ECS instances to a Classic Load Balancer (CLB) instance, make sure that the ECS instances and the CLB instance belong to the same region. Classic Load Balancer (CLB) distributes network traffic to ECS instances across zones.
  • By default, if the primary zone of a Classic Load Balancer (CLB) instance is active, network traffic is not distributed to the secondary zone. In this case, you cannot configure Classic Load Balancer (CLB) to distribute network traffic to the secondary zone. The secondary zone can serve your workloads only when the primary zone is down. For example, if power outages or fiber cuts occur in the primary zone, Classic Load Balancer (CLB) automatically distributes network traffic to the secondary zone. An unhealthy ECS instance does not trigger a zone failover.
  • ECS instances are independent from Classic Load Balancer (CLB). When the Classic Load Balancer (CLB) instance in the primary zone is down, the ECS instances can still provide services. For example, when the Classic Load Balancer (CLB) instance in Zone A is down, the Classic Load Balancer (CLB) instance in the secondary zone takes over. In this case, the Classic Load Balancer (CLB) instance in the secondary zone can distribute network traffic across the ECS instances in both zones. However, if the whole zone is down due to power outages or fiber cuts, all resources in this zone stop running, including the Classic Load Balancer (CLB) instance and the ECS instances.

Regions and zones that support IPv4 CLB instances

Region Primary zone
China (Qingdao) Zone B and Zone C
China (Beijing) Zone A, Zone B, Zone C, Zone D, Zone E, Zone F, Zone G, Zone H, Zone I, Zone J, and Zone K
China (Zhangjiakou) Zone A, Zone B, and Zone C
China (Hohhot) Zone A and Zone B
China (Ulanqab) Zone A, Zone B, and Zone C
China (Hangzhou) Zone B, Zone D, Zone E, Zone F, Zone G, Zone H, Zone I, Zone J, and Zone K
China (Shanghai) Zone A, Zone B, Zone C, Zone D, Zone E, Zone F, Zone G, and Zone L
China (Shenzhen) Zone A, Zone B, Zone C, Zone D, Zone E, and Zone F
China (Heyuan) Zone A and Zone B
China (Guangzhou) Zone A and Zone B
China (Chengdu) Zone A and Zone B
China (Hong Kong) Zone B, Zone C, and Zone D
Japan (Tokyo) Zone A and Zone B
Singapore (Singapore) Zone A, Zone B, and Zone C
Australia (Sydney) Zone A and Zone B
Malaysia (Kuala Lumpur) Zone A and Zone B
Indonesia (Jakarta) Zone A, Zone B, and Zone C
US (Virginia) Zone A and Zone B
US (Silicon Valley) Zone A and Zone B
Germany (Frankfurt) Zone A and Zone B
UK (London) Zone A and Zone B
India (Mumbai) Zone A and Zone B
UAE (Dubai) Zone A

Regions and zones that support IPv6 CLB instances

Table 1. Regions and zones that support IPv6 CLB instances on Alibaba Cloud
Region Zone
China (Beijing) Zone A, Zone B, Zone C, Zone D, Zone E, Zone F, Zone G, Zone H, Zone I, Zone J, and Zone K
China (Zhangjiakou) Zone A, Zone B, and Zone C
China (Hohhot) Zone A and Zone B
China (Ulanqab) Zone A, Zone B, and Zone C
China (Hangzhou) Zone B, Zone D, Zone E, Zone F, Zone G, Zone H, and Zone I
China (Shanghai) Zone A, Zone B, Zone C, Zone D, Zone E, Zone F, Zone G, and Zone L
China (Shenzhen) Zone A, Zone B, Zone C, Zone D, Zone E, and Zone F
China (Guangzhou) Zone A and Zone B
China (Chengdu) Zone A and Zone B
China (Hong Kong) Zone B, Zone C, and Zone D
Singapore (Singapore) Zone A, Zone B, and Zone C
US (Virginia) Zone A and Zone B
Germany (Frankfurt) Zone A and Zone B
Table 2. Regions and zones that support IPv6 CLB instances on Alibaba Finance Cloud
Region Zone
China (Hangzhou) Zone I and Zone H
China (Shanghai) Zone A, Zone B, Zone F, Zone G, and Zone K
China (Shenzhen) Zone A, Zone B, Zone D, and Zone E
Table 3. Regions and zones that support IPv6 CLB instances on Alibaba Gov Cloud
Region Zone
China (Beijing) Zone A, Zone B, Zone C, and Zone D