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 used.

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 to the origin server are sent to CDN nodes. This reduces the pressure 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.
• The client retrieves static resources from the closest CDN node. This minimizes the network transmission distance and ensures the quality of 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 the parameters to enable Alibaba Cloud CDN to accelerate the delivery of content from your ECS instance.
   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, 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	Description
      Domain Name to Accelerate	Enter the domain name that you want to add, such as example.com. Take note of the following limits: You can specify a domain name or a wildcard domain name. The domain name must be in lowercase letters, such as cdntest.example.com. Chinese characters are not supported. You can specify a wildcard domain name, such as *.example.com. For more information about the rules for adding wildcard domain names, see Rules for adding wildcard domain names. Note The specified wildcard domain name and the domain names that match the wildcard domain name must belong to the same Alibaba Cloud account. When you add a domain name to Alibaba Cloud CDN, Alibaba Cloud CDN verifies the ownership of the domain name. If the specified wildcard domain name and the domain names that match the wildcard domain name belong to different Alibaba Cloud accounts, an error message appears. To request technical support from Alibaba Cloud, submit a ticket. If a wildcard domain has never been added to Alibaba Cloud CDN, you can add domain names that match the wildcard domain name to Alibaba Cloud CDN by using different Alibaba Cloud accounts. You cannot add a duplicate domain name to Alibaba Cloud CDN. If a DomainAlreadyExist error occurs, check whether the domain name is already added to other Alibaba Cloud services such as ApsaraVideo VOD, ApsaraVideo Live, Dynamic Route for CDN (DCDN), Secure CDN (SCDN), and Video Surveillance. You can also submit a ticket to report this issue. You can add at most 50 domain names to Alibaba Cloud CDN for each Alibaba Cloud account. However, if the sum of the average daily peak bandwidth values of your domain names exceeds 50 Mbit/s, you can submit a ticket to add more domain names to Alibaba Cloud CDN. Make sure that the increase of domain names does not cause business risks. The content delivered from the domain name must be legal and comply with the Terms of Service for Alibaba Cloud CDN. For more information, see Limits.
      Business Type	Image and small file distribution: accelerates the delivery of small-sized static content on websites, such as e-commerce content and game images. Delivery of large files: accelerates the delivery of static files that are larger than 20 MB. ApsaraVideo for VOD: accelerates the delivery of audio or video content. DCDN: accelerates the delivery of both static and dynamic content. DCDN can accelerate the delivery of large amounts of dynamic content. If you set Business Type to DCDN, you must follow the instructions to go to the DCDN console to add and configure the domain name. For more information, see Add a domain name.
      Origin Info	Select 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 specified domain name of the origin server cannot be the same as the accelerated domain name. Otherwise, a DNS resolution loop occurs and requests cannot be redirected to the origin server.
      Port	Select a port based on the specified origin server. Port 80: Requests are redirected to the origin server through port 80. Port 443: Requests are redirected to the origin server through port 443. Make sure that the origin server supports HTTPS.
      Region	Select an accelerated region. If you select Mainland China Only or Global, you must apply for an Internet Content Provider (ICP) number for the domain name. We recommend that you use Alibaba Cloud ICP Filing System to apply for ICP numbers. It may take some time to update data in the database of Ministry of Industry and Information Technology (MIIT). After you submit domain name information to MIIT, we recommend that you wait 8 hours before you configure the domain name in Alibaba Cloud CDN. Note The pricing strategies vary based on the accelerated region. Choose an accelerated region based on your business requirements. For more information about the pricing of Alibaba Cloud CDN, see CDN Pricing. Mainland China Only: All requests are redirected to CDN nodes that are deployed in mainland China. Global: All requests are redirected to the nearest CDN nodes. Global (Excluding Mainland China): All requests are redirected to CDN nodes that are deployed outside mainland China.

   5. Click Next.
      If this is the first time the domain name is added to Alibaba Cloud CDN, Alibaba Cloud CDN must verify the ownership of the domain name. If the domain name has already passed the verification, skip this step. For more information, see Verify the ownership of a domain name.
   6. Wait for manual verification.

      It takes one to two business days to verify the ownership of a domain name. If the origin server is an ECS instance or an OSS bucket, you can submit a ticket. It takes less time to verify the ownership of an ECS instance or an OSS bucket.

      After the domain name passes the verification, you can check the status of the domain name on the Domain Names page. 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 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, find the domain name that you want to manage and click Configure in the Actions column.
   3. Click Add Record and add a CNAME record.
      Note

      • The CNAME record of a specific domain name takes precedence over that of a wildcard domain name. If the domain name to accelerate is a wildcard domain name, and the host record includes an asterisk (*), you must delete all effective DNS records of the second-level domain names that match the wildcard domain name.
      • If the CNAME record that you want to use conflicts with an existing DNS record, we recommend that you use another domain name or modify the DNS records.

      

      Parameter	Description	Example
      Type	Select CNAME from the drop-down list.	CNAME
      Host	Enter the prefix of the domain name.	If the domain name to accelerate is testcdn.aliyun.com, enter testcdn. If the domain name to accelerate is www.aliyun.com, enter www. If the domain name to accelerate is aliyun.com, enter @. If the domain name to accelerate is *.aliyun.com, enter *.
      ISP Line	Enter the default Internet service provider (ISP) line.	Keep the default setting.
      Value	Enter the CNAME of the domain name. Note Each accelerated domain name is assigned a unique CNAME. Second-level domain names cannot use the CNAME of the top-level domain name. If you need to accelerate a second-level domain name, add the second-level domain name to Alibaba Cloud CDN. Alibaba Cloud then assigns a CNAME to the second-level domain name. Alternatively, you can add a second-level wildcard domain name to Alibaba Cloud CDN. Domain names that match the wildcard domain name can be mapped to the CNAME of the wildcard domain name. For more information, see Add a domain name to Alibaba Cloud CDN.	all.example.com.w.kunlunsl.com
      TTL	Enter a TTL value for the CNAME record. A smaller value indicates a shorter time to apply record updates. The default TTL value is 10 minutes.	Keep the default setting.

   4. Click OK.
      After the CNAME record takes effect, acceleration is immediately enabled for the domain name. 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 about 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. Use an on-premises machine to check whether the CNAME record takes effect.
   1. Open Command Prompt in Windows.
   2. Run the ping command to ping the domain name. If the CNAME in the output is the same as the CNAME that is assigned to the domain name, it indicates that acceleration is enabled for the domain name.