Alibaba Cloud CDN is a virtual network that consists of globally distributed edge nodes. Alibaba Cloud CDN reduces loads on origin servers to prevent network congestion. You can use Alibaba Cloud CDN to accelerate content delivery for websites in different regions or scenarios.
Alibaba Cloud CDN provides more than 2,800 globally distributed edge nodes. Among these nodes, more than 2,300 are distributed across 31 provincial regions in mainland China and more than 500 are distributed across over 70 countries and regions, including Hong Kong (China), Macao (China), and Taiwan (China). The total bandwidth capacity of Alibaba Cloud CDN can reach up to 150 Tbit/s.
Alibaba Cloud CDN caches resources from origin servers to the globally distributed edge nodes. Users can retrieve resources from the nearest edge nodes instead of origin servers. This accelerates content delivery and reduces loads on origin servers. Some edge nodes support IPv6.
Alibaba Cloud CDN allows you to delivery content in an efficient and simple way. You do not need to change the current service structure or complete complex configurations. You can add domain names to be accelerated after a few simple steps in the Alibaba Cloud CDN console. Alibaba Cloud CDN accelerates content delivery by using the globally distributed edge nodes. For more information about how to activate and use Alibaba Cloud CDN, see Quick Start.
- Widely distributed nodes: Alibaba Cloud CDN redirects requests to the nearest nodes that belong to the same Internet service provider (ISP) as the clients. This accelerates long-distance content delivery and reduces network latency for cross-ISP content delivery.
- Scalable resources: Alibaba Cloud CDN provides more than 2,800 globally distributed edge nodes to ensure resource scalability and service availability.
- Accurate scheduling: Alibaba Cloud CDN monitors the health status of edge nodes in real time, and redirects requests to optimal nodes selected by the scheduling system based on client locations and ISPs. This improves the acceleration performance.
- Intelligent connections: Alibaba Cloud CDN uses optimization strategies such as protocol optimization and connection optimization to reduce network latency and accelerate content delivery, especially over unstable networks.
- Efficient caching: Alibaba Cloud CDN increases the cache hit ratio because requests can hit cache on the nearest edge nodes. This accelerates content delivery.
- Lower IT expenses: Edge nodes provide computing, bandwidth, and connection resources. This reduces IT expenses.
- High bandwidth capacity: The total bandwidth of Alibaba Cloud CDN can reach up to 150 Tbit/s.
- Standardized API: The Alibaba Cloud CDN API is easy to use and supports various operations.
For more information, see Benefits.
- Scheduling system
The scheduling system provides a policy center and supports Domain Name System (DNS) resolution, HTTPDNS, and 302 redirection. After a client sends a request, the request is resolved by DNS resolution and then processed by the scheduling system.
- Link quality system
The link quality system monitors the loads and health status of all nodes and links in real time, and reports monitoring data to the scheduling system. Then, the scheduling system selects an optimal access point for requests based on the IP address information such as the Internet service provider (ISP) and region of the requests.
- Caching system
The caching system redirects requests to edge nodes based on the access points of the requests. If the requested resource is already cached on the edge nodes, the resource is directly returned to the client. If the requested resource is not cached on L1 or L2 nodes, the request is redirected to the origin server to retrieve the resource. Then, the retrieved resource is returned to the client and cached on the edge nodes. Subsequent requests can directly retrieve the resource from the edge nodes. Alibaba Cloud CDN uses a multi-level cache hierarchy to accelerate content delivery, reduce the amount of bandwidth resources consumed by the back-to-origin process, and improve user experience.
- Support system
The support system supports Tianyan, also known as the Five-hundred-meter Aperture Spherical radio Telescope (FAST), data intelligence, and configuration management. The support system can monitor resources, analyze data, and manage configurations.
- Resource monitoring: Tianyan can monitor the status of services that are running in the caching system. For example, Tianyan can monitor the number of queries per second (QPS), bandwidth, and HTTP status codes for a domain name that is accelerated by Alibaba Cloud CDN.
- Data analytics: You can analyze data, such as the top N most frequently requested URLs, page views, and unique visitors for a domain name that is accelerated by Alibaba Cloud CDN.
- Configuration management: You can create and manage cache expiration rules to improve the efficiency of the caching system. For example, you can create a cache expiration rule for a specified type of file or enable parameter filtering.
How it works
The following example shows how Alibaba Cloud CDN works.
www.a.com, and acceleration is enabled. The following figure shows how Alibaba Cloud CDN works after it receives an HTTP request from a client in Beijing.
- When the client in Beijing sends a request to retrieve resources from
www.a.com, a domain name resolution request is sent to the local DNS server (LDNS).
- The LDNS checks whether the cache contains an IP address record that corresponds to
www.a.com. If so, the LDNS directly returns the IP address to the client. If not, the LDNS queries the IP address from the authoritative DNS.
- After the authoritative DNS resolves
www.a.com, it returns the IP address of the corresponding Canonical Name (CNAME)
- The LDNS sends the domain name resolution request to the Alibaba Cloud DNS scheduling system. Alibaba Cloud DNS selects the IP address of an optimal node for the request.
- The LDNS receives the resolved IP address returned by Alibaba Cloud DNS.
- The client receives the resolved IP address.
- The client initiates a request to the received IP address.
- If the edge node that corresponds to the IP address (the node in Beijing in this example) has cached the requested resource, the resource is directly returned to the client, as shown in steps 7 and 8 in the preceding figure. Then, the request ends.
- If the edge node that corresponds to the IP address has not cached the resource, the edge node redirects the request to the origin server to retrieve the resource. The retrieved resource is returned to the client and cached on edge nodes (the node in Beijing in this example) based on the cache expiration rules. Then, the request ends. For more information about how to configure a cache expiration rule, see Create a cache expiration rule.
Differences between Alibaba Cloud CDN and DCDN
|Item||Alibaba Cloud CDN||Dynamic Route for CDN (DCDN)|
|Typical scenarios||Game updates, app updates for mobile phones, on-demand videos including long and short videos, and infographic websites.||Online shops, online payments, online chatting, online education, online multiplayer games, and financial management.|
|Acceleration methods||Accelerates the delivery of static content and redirects requests for dynamic content
to origin servers. Alibaba Cloud CDN is suitable for scenarios that require high bandwidth
and process a large amount of network traffic.
||Accelerates the delivery of dynamic content, or both dynamic and static content
Supports DNS resolution, HTTPDNS, and 302 redirection.
Supports DNS resolution, HTTPDNS, and 302 redirection.
For more information about static and dynamic content, see What are static content and dynamic content?.
|Media website||Purpose-specific website||Resource distribution website|
For more information, see Scenarios.
- Billing of basic services: supports the pay-by-data-transfer and pay-by-peak-bandwidth metering methods. The default metering method is pay-by-data-transfer. For more information, see Billing of basic services.
- Billing of value-added services: The billable items include HTTPS requests for static content, QUIC requests for static content, and real-time log entries. For more information, see Billing of value-added services.
For more information, see CDN Pricing.
We recommend that you familiarize yourself with the billing rules of Alibaba Cloud CDN before you activate Alibaba Cloud CDN. For more information, see Activate Alibaba Cloud CDN.
- Alibaba Cloud CDN console
- Alibaba Cloud CDN API
The Alibaba Cloud CDN API is a remote procedure call (RPC) API that supports GET and POST requests. For more information, see API Reference.
- Use Alibaba Cloud CDN to accelerate the delivery of resources in OSS buckets (Method 1)
- Use Alibaba Cloud CDN to accelerate the delivery of resources in OSS buckets (Method 2)
- Use Alibaba Cloud CDN to accelerate the delivery of resources on ECS instances
- Causes of and solutions to low cache hit ratios
|DCDN||DCDN separates dynamic content from static content, and accelerates the delivery of both static and dynamic content.|
|OSS||If you use an OSS bucket as an origin server, you can use Alibaba Cloud CDN to accelerate content delivery and reduce Internet data transfer fees.|
|ApsaraVideo Live||You can use Alibaba Cloud CDN together with ApsaraVideo Live to achieve media feed storage, video segmentation and transcoding, access authentication, and content delivery acceleration.|
|ApsaraVideo VOD (VOD)||You can use Alibaba Cloud CDN together with VOD to reduce the buffer time and improve playback smoothness.|
|Alibaba Cloud DNS||You can use Alibaba Cloud DNS that is highly available and stable to ensure smooth access to resources.|
|ECS||You can use Alibaba Cloud CDN together with ECS to improve website availability, protect information about origin servers, and minimize bandwidth usage costs.|
|Server Load Balancer (SLB)||You can specify the IP address of an SLB instance as the origin address to balance loads during the back-to-origin process.|