This topic describes the concepts of DNS resolution and canonical name (CNAME) record.

After you add a domain name to ApsaraVideo Live, ApsaraVideo Live assigns a canonical domain name to the domain name. To use ApsaraVideo Live, you must configure a CNAME record at your DNS service provider to map the domain name to the canonical domain name. This way, requests that are sent to the domain name for CDN can be redirected to the nearest Alibaba Cloud CDN node.

Note A time-to-live (TTL) value is specified in the CNAME record of a domain name to indicate how long the CNAME record can be cached on the DNS resolver. If you modify the CNAME record of the domain name, the new settings take effect after the cache expires, which takes about 10 minutes.

What is DNS resolution?

If you are new to DNS resolution and have questions about what is DNS resolution, why is DNS resolution required, how to perform DNS resolution, what is an A record, what is a CNAME record, and what are the differences between a CNAME record and an A record, see the What is DNS resolution?.

Before you configure a CNAME record, you must understand the concepts of CNAME record and canonical domain name.

  • CNAME record

    A CNAME record is an alias record that is used to map a domain name to another domain name that provides an IP address.

    For example, you have a server that stores a large amount of data and you use the domain name docs.example.com to access the data. However, you also want to use the domain name documents.example.com to access the data. In this case, you can add a CNAME record at your DNS service provider to map documents.example.com to docs.example.com. After you add the CNAME record, all requests that are sent to documents.example.com are redirected to docs.example.com.

  • Canonical domain name

    After you activate ApsaraVideo Live and add a domain name to ApsaraVideo Live, ApsaraVideo Live assigns a canonical domain name to the domain name. The canonical domain name is in the format of *.*kunlun*.com. You must add a CNAME record at your DNS service provider to map your domain name to the canonical domain name in the format of *.*kunlun*.com. After the CNAME record takes effect, all requests that are sent to the domain name are redirected to the nearest Alibaba Cloud CDN node. This accelerates content delivery.

Configure a CNAME record for ApsaraVideo Live

Note
  • If you encounter a conflict when you add a CNAME record, you can change the domain name or modify the CNAME record.
  • You must configure CNAME records for both the streaming domain and the ingest domain.

Check whether the CNAME records take effect

  • The duration before a new CNAME record takes effect depends on the DNS service provider. You can run the ping or dig command on the ingest domain or streaming domain that you have added. If you are redirected to *.*kunlun*.com, the CNAME record takes effect, which indicates that the ingest domain or streaming domain takes effect.
  • You can also check whether the CNAME record takes effect on the Domain Management page in the ApsaraVideo Live console.
    Note If no exclamation point (!) is displayed in the CNAME column, the CNAME record takes effect.
An exclamation point (!) may be displayed due to the following reasons:
  • The canonical domain name that you specify in the CNAME record is inconsistent with that displayed in the ApsaraVideo Live console.
  • After you modify a CNAME record, the new settings take effect after the cache on the DNS resolver of the ISP expires. A CNAME record is usually cached on the DNS resolver for 10 minutes, which is subject to the TTL that you specify when you configure the CNAME record.
  • The domain name is not mapped to the canonical domain name assigned by ApsaraVideo Live in specific regions. The CNAME record must globally take effect.