When you configure CNAME, a resolution failure may occur or the console may prompt a message that indicates improper resolution. This topic describes the common causes of and solutions to the preceding issues.
- Cause 1: Resolution records conflict.
Resolution records conflict when you configure CNAME, which causes resolution failure.Solution: When you configure CNAME, resolution records conflict in two ways, as shown in the following table. If your domain name has a previous A record or MX record, make sure that the domain name is no longer used before you implement the following solutions. You can also use a new domain name.
Conflict Solution The CNAME record conflicts with an A record You must delete the A record before you add a CNAME record.Note When you delete the A record, the access of ApsaraVideo Live is not affected because the requests of the client are sent to ApsaraVideo Live nodes after the CNAME record is added. The CNAME record conflicts with an MX record You can resolve the issue by using URL forwarding.Notice Make sure that both the source and destination domain names have a valid Internet Content Provider (ICP) number. For more information about the configuration of URL forwarding, see Resolution record configurations in the following table. Table 1. Resolution record configurations Record type Host record ISP line Record value TTL URL @ Default
10 minutes MX @ Default
- Cause 2: Resolution records are added to a subdomain.
If the domain name that you add to ApsaraVideo Live is a subdomain, the resolution records of the domain name are added to the subdomain, which causes resolution failure.
Solution: Add the correct resolution records and host record to the root domain name to which the subdomain belongs. You do not need to add the subdomain to the Domain Name System (DNS) provider.
- Cause 3: The resolution record value is not the same as the obtained CNAME address.
The resolved CNAME record value is not the same as the CNAME address that is obtained in the Alibaba Cloud CDN console, which causes resolution failure.
Solution: Make sure that the resolved CNAME record value and the CNAME address that is obtained in the Alibaba Cloud CDN console are the same.
Improper resolution does not mean that the operation failed. The following section describes the reasons that may cause the console to prompt a message that indicates improper resolution.
- Cause 1: The time to live (TTL) is not reached.
After you add a CNAME record, the TTL of the CNAME record is not updated on the DNS server of your Internet service provider (ISP). Typically, the TTL is 10 minutes. The actual TTL that you specify when you configure the CNAME record shall prevail.
- Cause 2: The CNAME record is not applied to all CDN nodes.
After you add a CNAME record, Alibaba Cloud CDN checks whether the CNAME record takes effect on all CDN nodes. If not, the accelerated domain name cannot be resolved to IP addresses of all CDN nodes. In this case, an exclamation mark (!) is displayed.
- Cause 3: The ISP lines are different.
The accelerated domain name is not resolved to IP addresses of all CDN nodes, such as nodes outside the Chinese mainland, because an ISP line is specified for the CNAME record, as shown in the following figure. For ISP lines to which CDN does not apply, A records are resolved to the server. The Alibaba Cloud CDN console does not display any message that indicates improper resolution for these lines. In this case, your use of the services is not affected.