Add a CNAME record for a domain name to accelerate content delivery - Edge Security Acceleration

After you add a domain name to Dynamic Content Delivery Network (DCDN), the system assigns a CNAME to the domain name. You must add a CNAME record in the system of your DNS service provider to map the domain name to the CNAME before requests can be redirected to points of presence (POPs). This enables content delivery acceleration, edge computing, and protection of web resources.

Background information

How it works

After you add a domain name to DCDN, the system assigns a CNAME to the domain name, which points to globally distributed POPs. Requests are forwarded to POPs. If the requested content is cached on the POPs, the content is returned. Otherwise, the POPs retrieve the content from the origin and cache it for subsequent requests. This way, DCDN accelerates content delivery and improves user experience. After you add a CNAME record for a domain name, make sure that the DNS record of the origin server points to the CNAME record provided by DCDN. This way, traffic to your website goes through POPs.

Domain name resolution

Domain name resolution is the process of converting a domain name, such as example.aliyundoc.com, into an IP address of the client. For more information, see What is DNS resolution?

Prerequisites

A domain name is added by following instructions in Add a domain name.

Step 1: Obtain the CNAME of the accelerated domain name

Go to the Domain Names page in the DCDN console and copy the CNAME of the accelerated domain name.

Step 2: Add a CNAME record

The procedure to add a CNAME record varies with your DNS service provider.

If your DNS service provider is Alibaba Cloud, see Add a CNAME record on Alibaba Cloud.
If your DNS service provider is Tencent Cloud, see Add a CNAME record on Tencent Cloud.

Important

Make sure that the DNS records do not conflict with each other in the same system.
The server that DCDN uses for domain name resolution is deployed in the Chinese mainland. If you configure region-specific DNS settings for your domain name, for example, you add a CNAME record for your DCDN-accelerated domain name only in regions outside the Chinese mainland, including Hong Kong (China), Macao (China), and Taiwan (China), the domain name cannot be mapped to the CNAME. The CNAME status is Pending Configuration in the DCDN console. However, acceleration for the domain name is not affected.
CNAMEs that are assigned by Alibaba Cloud CDN, DCDN, ApsaraVideo Live, and ApsaraVideo VOD can be used only for domain name resolution. If Alibaba Cloud detects that your CNAME is used for unauthorized or malicious activities, Alibaba Cloud reserves the right to close your Alibaba Cloud account and remove the domain names.

Add a CNAME record on Alibaba Cloud

If your DNS service provider is Alibaba Cloud, perform the following steps to add a CNAME record for the domain name:

Log on to the Alibaba Cloud DNS console with the Alibaba Cloud account to which the domain name belongs.
Optional. In the Alibaba Cloud DNS console, add a domain name that is not registered with Alibaba Cloud.
Note
If the domain name is not registered through Alibaba Cloud Domains, you must add the domain name to Alibaba Cloud DNS before you can add a DNS record for it. For more information, see Manage domain names. If the domain name is registered with Alibaba Cloud, skip this step.
On the Domain Name Resolution page, find your domain name and click DNS Settings in the Actions column.

Click Add DNS Record to add a record.

Note

The CNAME record of a specific domain takes precedence over that of a wildcard domain. If you want to accelerate a wildcard domain, where the DNS record contains an asterisk (*), you need to delete all other DNS records that match the wildcard domain.

添加记录

Parameter	Description	Example
Record Type	Select CNAME from the drop-down list.	CNAME
Hostname	For root domains, enter `@`. For wildcard domains, enter `*`. For subdomains, enter the prefix of the subdomain.	Root domains aliyundoc.com: `@` aliyundoc.com.cn: `@` Wildcard domains .aliyundoc.com: `` .aliyundoc.com.cn: `` .example.aliyundoc.com: `.example` .example.aliyundoc.com.cn: `.example` Subdomains example.aliyundoc.com: `example` example.aliyundoc.com.cn: `example` www.example.aliyundoc.com: `www.example` www.example.aliyundoc.com.cn: `www.example` Note .com.cn is a top-level domain that consists of two hierarchical levels.
DNS Request Source	Select Default from the drop-down list.	We recommend that you keep the default setting.
Record Value	Enter the CNAME of the domain. Note Each accelerated domain name is assigned a unique CNAME. Subdomains cannot use the CNAME of the root domain. If you want to accelerate a subdomain, add the subdomain to DCDN. Alibaba Cloud then assigns a CNAME to the subdomain. Alternatively, you can add a wildcard domain name to DCDN. Subdomains that match the wildcard domain name are mapped to the CNAME of the wildcard domain name. For more information, see Add a domain name.	www.example.com.w.kunlunsl.com
TTL	Enter a time-to-live (TTL) value for the record. A smaller value indicates that the record is updated quicker. The default TTL value is 10 minutes.	We recommend that you keep the default setting.

Click OK.

Add a CNAME record on Tencent Cloud

If your DNS service provider is Tencent Cloud, perform the following steps to add a CNAME record for the domain name:

Log on to the DNSPod console.

On the DNSPod page, click Add Records and add a CNAME record.

Parameter	Description	Example
Host	For root domains, enter `@`. For wildcard domains, enter `*`. For subdomains, enter the prefix of the subdomain.	Root domains aliyundoc.com: `@` aliyundoc.com.cn: `@` Wildcard domains .aliyundoc.com: `` .aliyundoc.com.cn: `` .example.aliyundoc.com: `.example` .example.aliyundoc.com.cn: `.example` Subdomains example.aliyundoc.com: `example` example.aliyundoc.com.cn: `example` www.example.aliyundoc.com: `www.example` www.example.aliyundoc.com.cn: `www.example` Note .com.cn is a top-level domain that consists of two hierarchical levels.
Type	Select CNAME from the drop-down list.	CNAME
Split Zone	Select Default.	We recommend that you keep the default setting.
Value	Enter the CNAME of the domain. Note Each accelerated domain name is assigned a unique CNAME. Subdomains cannot use the CNAME of the root domain. If you want to accelerate a subdomain, add the subdomain to DCDN. Alibaba Cloud then assigns a CNAME to the subdomain. Alternatively, you can add a wildcard domain name to DCDN. Subdomains that match the wildcard domain name are mapped to the CNAME of the wildcard domain name. For more information, see Add a domain name.	www.example.com.w.kunlunsl.com
Weight	You do not need to set this parameter.	N/A
MX	You do not need to set this parameter.	N/A
TTL	Enter a TTL value for the CNAME record. A smaller value indicates that the record is updated quicker.	We recommend that you keep the default setting.

Click Confirm.

Step 3: Verify that the CNAME record takes effect

Method 1: Use the DCDN console
1. Log on to the DCDN console and navigate to the Domain Names page.
2. Find the domain name and move the pointer over the CNAME Status column. If the CNAME status is Configured, the CNAME has taken effect.
Method 2: Run the nslookup command
1. Start Command Prompt in Windows or Terminal in macOS or Linux.
2. Run the nslookup -type=CNAME domainName command. If the CNAME in the output is the same as the CNAME that is assigned to the domain name in the DCDN console, DCDN acceleration takes effect for the domain name.

References

If the cache hit ratio is lower than expected after you use DCDN to accelerate content delivery for a domain name, you can configure and enable the prefetch feature. The prefetch feature allows DCDN to prefetch content from origin servers to DCDN POPs during off-peak hours. This increases the cache hit ratio. For more information, see Purge and prefetch resources.