Common issues with CNAME resolution

Resolution failure

• Cause 1: Conflicting resolution records.

  A resolution failure can occur if your new CNAME record conflicts with existing resolution records for the same host record.

  Solution: When you configure a CNAME record, two types of conflicts can occur, as shown in the following table. If your domain name already has an A record or MX record, ensure that the domain name is no longer in use before proceeding. Alternatively, you can use a new domain name.

  Conflict	Solution
  The CNAME record conflicts with an A record	Delete the A record before you configure the CNAME record. Note Deleting the A record does not affect access to ApsaraVideo Live because client requests are routed to ApsaraVideo Live nodes after you configure the CNAME record.
  The CNAME record conflicts with an MX record	You can use URL forwarding to resolve the conflict between the CNAME record and the MX record. Important Both the source and destination domain names for URL forwarding must have a valid Internet Content Provider (ICP) filing. For configuration details, see the Resolution record configuration table.

  Table 1. Resolution record configuration

  Record type	Host record	ISP line	Record value	TTL
  URL	@	Default	example.com	10 minutes
  MX	@	Default	***.aliyundoc.com	10 minutes

• Cause 2: Resolution record added to a subdomain.

  If the domain name that you add to ApsaraVideo Live is a subdomain, a resolution failure can occur if you incorrectly add the resolution record to the subdomain itself.

  Solution: Add the correct resolution record and host record to the subdomain's root domain name. You do not need to create a new, separate subdomain with your DNS provider.

• Cause 3: Mismatch between the record value and the obtained address.

  A resolution failure occurs if the record value for the CNAME record does not match the CNAME address obtained from the Alibaba Cloud CDN console.

  Solution: Verify that the configured record value for the CNAME record matches the CNAME address provided in the Alibaba Cloud CDN console.

Improper resolution

This status does not indicate an operation failure. It may appear for several common reasons:

• Cause 1: The TTL has not expired.

  After you configure the CNAME record, the TTL (Time to Live) of the record on ISP DNS servers may not have expired. It takes time for the change to propagate. The TTL is typically 10 minutes, but the actual time depends on the value you specified during configuration.

• Cause 2: Resolution has not propagated globally.

  After you configure a CNAME record, Alibaba Cloud CDN performs a global check to verify that the accelerated domain name resolves correctly. If the resolution has not propagated in some regions, the console may display a warning. The status returns to normal after the resolution propagates globally.

• Cause 3: Different ISP lines are used.
  When you configure domain name resolution, you can set specific ISP lines. Some traffic, such as from regions Outside Chinese mainland, might be intentionally configured not to use Alibaba Cloud CDN for acceleration. For these non-accelerated ISP lines, the resolution is typically handled by an A record pointing to your origin server. Because these routes do not resolve to Alibaba Cloud CDN, the console reports an improper resolution. This status is expected and does not affect your services. In the Edit Record dialog box of your DNS settings, the Query Source drop-down list provides options including: Default, China Unicom, China Telecom, China Mobile, China Education and Research Network, Outside Chinese mainland, and Baidu.