Server Load Balancer:ALB instance overview

DNS name

Starting from 00:00:00 on November 15, 2024 (UTC+8), new ALB instances use upgraded domain names by default: xxx.alb.aliyuncsslb.com for instances in the Chinese mainland and xxx.alb.aliyuncsslbintl.com for instances outside the Chinese mainland.

You cannot access new ALB instances directly by their DNS names. You must use CNAME resolution to map your custom domain name to the instance's DNS name. This allows you to access the instance through your custom domain name.

Instance network type

You can change the network type of an ALB instance to switch between Internet-facing and internal types.

Instance type	Internet-facing instance	Internal instance
Use case	Provides access to backend services from the public network.	Provides access to backend services only from within a VPC.
IP address allocation	Assigns an EIP and a private IP address. You can associate an Anycast EIP with an ALB instance to provide low-latency access for multi-region services.	Assigns only a private IP address.
Access method	Accessible from the public network and private networks.	Accessible only from private networks.
Diagram
Billing	Incurs an instance fee, an LCU fee, and public network data transfer fees (charged by the EIP).	Incurs only an instance fee and an LCU fee.

IP version

WAF integration

• Alibaba Cloud recommends enabling Web Application Firewall (WAF) 3.0 protection for an ALB instance by using service-based integration. This method uses WAF-enhanced ALB instances.

  • Supported regions:

    Area	Region
    China	China (Chengdu), China (Qingdao), China (Beijing), China (Guangzhou), China (Hangzhou), China (Ulanqab), China (Shanghai), China (Shenzhen), China (Zhangjiakou), and China (Hong Kong)
    Asia Pacific	Philippines (Manila), Indonesia (Jakarta), Japan (Tokyo), Malaysia (Kuala Lumpur), Singapore, Thailand (Bangkok), and South Korea (Seoul)
    Europe and Americas	Germany (Frankfurt), US (Virginia), US (Silicon Valley), and Mexico
    Middle East	SAU (Riyadh - Partner Region), UAE (Dubai)

  • WAF version: You must use WAF 3.0. If you have a WAF 2.0 instance in your account, you must first release the WAF 2.0 instance or migrate it to WAF 3.0.

    By default, ALB does not enable the X-Forwarded-Proto header in requests forwarded to the backend server group. After you terminate a WAF 2.0 instance, accessing the ALB directly may cause service exceptions, such as infinite loop redirection, because the backend service cannot properly identify the protocol (HTTP/HTTPS). To prevent this issue, you must manually enable the X-Forwarded-Proto request header in the ALB listener configuration.

  • Feature availability: WAF for ALB instances does not support the following features: the data leakage prevention module and the automatic Web SDK integration feature for anti-crawler rules for websites in the bot management module.

• If you need to use an existing WAF 2.0 instance, you can use transparent integration for Internet-facing Basic and Standard ALB instances in the following regions: China (Hangzhou), China (Shanghai), China (Shenzhen), China (Chengdu), China (Beijing), and China (Zhangjiakou). internal ALB instances do not support integration with WAF 2.0.

Cross-zone load balancing

By default, cross-zone load balancing is enabled for ALB instances. Incoming requests are distributed to backend services deployed in all selected zones within the specified region. If you disable this feature for a server group, loads are balanced across each single zone.

Instance status