This topic describes the causes of and solutions to ineffective CNAME records.
A CNAME may fail to take effect due to the following causes:
- The CNAME is incorrect. Check whether the CNAME in the CNAME record is the same as the one assigned in the Alibaba Cloud CDN console. If they are different, DNS resolution fails.
- The time-to-live (TTL) value of the CNAME record has not been updated. It typically takes 10 minutes for the system to update the TTL value. The time that it takes may vary based on the TTL value.
- The CNAME record is not applied to all CDN edge nodes. After you add a CNAME record, Alibaba Cloud CDN checks whether it takes effect on all edge nodes. If not, the accelerated domain name cannot be resolved to all CDN edge nodes. In this case, an exclamation mark (!) is displayed.
- The accelerated domain name is not resolved to all CDN edge nodes because an Internet service provider (ISP) line is specified in the CNAME record, as shown in the following figure. In this case, requests transmitted over ISP lines in mainland China are sent to CDN edge nodes, but requests transmitted over ISP lines outside mainland China are sent to the server based on the A record. The console may display an error but Alibaba Cloud CDN is working as expected.