Use Alibaba Cloud CDN to accelerate the delivery of resources from ECS instances

Alibaba Cloud Content Delivery Network (CDN) can cache static resources stored on Elastic Compute Service (ECS) instances to accelerate the delivery of the resources. ECS instances can store both static and dynamic resources. When a client requests dynamic resources from an ECS instance, the ECS instance returns the requested resources to the client. When a client requests static resources from an ECS instance, if the CDN node nearest to the client has cached the requested resources, the CDN node returns the cached resources to the client. This way, the delivery of the static resources is accelerated. This topic describes how to enable Alibaba Cloud CDN to accelerate the delivery of resources on ECS instances in the Alibaba Cloud CDN console and the scenarios where Alibaba Cloud CDN can be applied.

Background information

Alibaba Cloud CDN works with a precise scheduling system. This system redirects requests for static resources to CDN nodes that are nearest to the clients. This mechanism enables efficient retrieval of required resources and minimizes network congestion.

An ECS instance stores dynamic resources such as web applications and databases, and static resources such as static scripts, images, attachments, audio files, and video files. CDN nodes cache static resources rather than dynamic resources from the ECS instance. When a client requests to access or download dynamic resources, the ECS instance returns the requested resources to the client. When a client requests static resources that are cached on CDN nodes, the scheduling system redirects the request to the CDN node nearest to the client. Then, the CDN node returns the cached resources to the client. The following figure shows how Alibaba Cloud CDN accelerates the delivery of resources from an ECS instance.

In this case, the ECS instance is the origin server. The delivery of content stored on the ECS instance is accelerate by Alibaba Cloud CDN. Users retrieve files from the nearest CDN node. This architecture provides the following benefits:

• All requests destined for the origin server are redirected to CDN nodes. This reduces the workloads on the origin server.
• Compared with data transfer between clients and ECS instances over the Internet, data transfer between clients and CDN nodes is billed at a lower price rate.
• Clients retrieve static resources from the nearest CDN nodes. This minimizes the network transmission distance and ensures the quality of the retrieved resources.

In the following example, Alibaba Cloud DNS is used to demonstrate how to configure a Canonical Name (CNAME) record.

1. In the OSS console, set parameters to enable Alibaba Cloud CDN to accelerate the delivery of content from your ECS instance.
   1. Log on to theAlibaba Cloud CDN console.
   2. In the left-side navigation pane, click Domain Names.
   3. On the Domain Names page, click Add Domain Name.
   4. On the Add Domain Name page, set the following parameters and set Origin Info to IP or Site Domain.

      Parameter	Value	Description
      Domain Name to Accelerate	-	Enter the domain name that you want to add to Alibaba Cloud CDN, for example, ch.aliyun.com. Note that: You can use a subdomain name or a wildcard domain name as the accelerated domain name, for example, cdntest.example.com. Wildcard domain names are supported and Chinese domain names are not supported. Follow the instructions to enter a wildcard domain name, for example, *.test.com. You cannot add a duplicate domain name to Alibaba Cloud CDN. If a DomainAlreadyExist error occurs, submit a ticket. You can add at most 50 domain names to Alibaba Cloud CDN under each Alibaba Cloud account. To add more domain names, submit a ticket. Content that is delivered from your domain name must comply with the limits of Alibaba Cloud CDN and the relevant regulations. For more information, see Limits.
      Business Type	Image and Small File	If you want to accelerate the delivery of small-sized static content on your website, we recommend that you select Image and Small File from the Business Type drop-down list. Examples of small-sized static content include small-sized files, images, and style sheets.
      	Delivery of large files	If you want to accelerate the delivery of static files larger than 20 MB, we recommend that you select Large File Download from the Business Type drop-down list. Examples of large-sized static files include game installation packages, app update packages, mobile read-only memory (ROM) upgrade packages, and app packages.
      	VOD	If you want to accelerate the delivery of on-demand video or audio content, we recommend that you select VOD from the Business Type drop-down list.
      	DCDN	If your website or application contains large amounts of dynamic content, you can select DCDN from the Business Type drop-down list. After simple configurations, Dynamic Route for CDN (DCDN) can accelerate the delivery of dynamic and static content separately. Static content is cached and dynamic content is retrieved from the origin server based on the optimal link algorithm and protocol layer optimization of Alibaba Cloud. After you select DCDN, you are prompted to go to the DCDN console. You can then create and configure the domain name. For more information, see Add a domain.
      Origin Info	IP or Site Domain	IP: Enter the public IP address of your server. You can enter multiple IP addresses. Site Domain: Enter the domain name of your origin server. You can enter multiple domain names. Note The domain name of the origin server that you specified cannot be the same as the accelerated domain name. Otherwise, a DNS resolution loop occurs and requests cannot be redirected to the origin server correctly. For example, if the domain name of your origin server is img.yourdomain.com, you can set the accelerated domain name to cdn.yourdomain.com.
      Port	-	Select a port based on your business requirements. Port 80 Data is transmitted over HTTP. Port 443 Data is transmitted over HTTPS.
      Region	Global (Excluding Mainland China)	If you select Global (Excluding Mainland China), you do not need to obtain an Internet Content Provider (ICP) number for the domain name.
      	Global	If you select Global, you must obtain an ICP number for the domain name. For more information, see Apply for an Internet Content Provider (ICP) number for an accelerated domain name.
      	Mainland China Only	If you select Mainland China Only, you must obtain an ICP number for the domain name. For more information, see Apply for an Internet Content Provider (ICP) number for an accelerated domain name.

      
   5. Click Next.
      After your domain name passes the review, you can view the domain name on the Domain Names page in the Alibaba Cloud CDN console. If the domain name is in the Enabled state, it indicates that the domain name is added to Alibaba Cloud CDN.
2. Log on to the Alibaba Cloud CDN console and obtain the CNAME assigned to the domain name.
   1. Log on to the Alibaba Cloud CDN console.
   2. In the left-side navigation pane, click Domain Names.
   3. On the Domain Names page, copy the CNAME of the accelerated domain name.
      
3. In the Alibaba Cloud DNS console, add a CNAME record for the domain name.
   1. Log on to the Alibaba Cloud DNS console.
   2. On the Manage DNS page, click the Domains tab, select the domain name that you want to manage, and then click Configure in the Actions column.
   3. Click Add Record and add a CNAME record.
      

      • Type: Select CNAME from the drop-down list.
      • Host: Enter the prefix of the accelerated domain name.

        Accelerated domain name	Host
        testcdn.aliyun.com	testcdn
        www.aliyun.com	www
        aliyun.com	@
        *.aliyun.com	*

      • ISP Line: Use the default value.
      • Value: Enter the CNAME assigned to the accelerated domain name.
      • TTL: Use the default value.
   4. Click OK.
      The CNAME record is added. After the CNAME record takes effect, CDN acceleration is automatically enabled for the domain name.

      Note

      • After you add a CNAME record, it immediately takes effect. After you modify a CNAME record, the modifications take effect within 72 hours.
      • After you add a CNAME record, it takes approximately 10 minutes for the system to update the status in the console. The system may prompt that you must add a CNAME record. Ignore the message.
4. On an on-premises machine, check whether the CNAME record works as expected.
   1. Open the Command Prompt in Windows.
   2. Use the Command Prompt to ping the accelerated domain name. If the CNAME in the output matches the CNAME assigned to the accelerated domain name in the Alibaba Cloud CDN console, it indicates that the CDN service is enabled for the domain name.