CNAME Auto Switch provides the failover capability that when an ISP line of an Anti-DDoS Pro instance encounters a problem, the service can be automatically switched to a healthy line, ensuring the service continuity and availability.
For example, you enable CNAME Auto Switch for a domain protected by an Anti-DDoS Pro instance that has China Telecom and China Unicom two lines.
- When the IP address of the China Telecom line fails, the Anti-DDoS Pro service can automatically switch to the IP address of the China Unicom line that works normally.
- When both IP addresses of the China Telecom line and the China Unicom line fail, CNAME Auto Switch cannot work.
Note: After you enable CNAME Auto Switch, when an IP address fails or is thrown into a black hole, the auto switch can be completed within one minute. The same CNAME is resolved to another healthy IP address on the DNS server. However, the actual time required for the changes to come into effect on the client depends on local DNS caching and updating.
Note: To enable the CNAME automatic scheduling function, your web service must Access to Anti-DDoS Pro through CNAME.
Log on to the Anti-DDoS Pro console.
Go to Protection>Setting>Web Attack Protection page, select Instance, and select Domain.
Locate the CNAME Auto Switch area, click to enable the CNAME automatic scheduling function.
Note: You can also go to Access>Web Service page, locate your protected domain, and click to enable CNAME Auto Switch directly.
Note: For the same domain name, if you enable this function in any of the lines, the configuration is automatically synchronized to other lines.
No additional modifications on DNS configuration is needed, because Alibaba Cloud automatically updates the DNS resolution.