When Alibaba Cloud DCDN accelerates the delivery of static resources to a user, it retrieves the resources from the origin server and caches them on the DCDN edge node that is nearest to the user. When the resources are requested again, the DCDN edge node directly returns the cached resources to the user. This accelerates content delivery. All the edge nodes of Alibaba Cloud DCDN are equipped with a caching system. When a user or an origin server interacts with an edge node, the caching system responds to user requests or processes responses from the origin server. For example, the caching system specifies a time-to-live (TTL) for cached resources or rewrites back-to-origin requests.

DCDN supports the following caching features.
Feature Description
Configure cache duration rules Allows you to configure cache expiration rules for static resources in a specified directory or with specified file extensions. In each cache expiration rule, you can set a TTL for the cached static resources and a priority for the rule. DCDN edge nodes cache and expire static resources based on the cache expiration rules.
Create a cache expiration rule for HTTP status codes Allows you to set a TTL for HTTP status codes that are returned to requests for resources in a specified directory or with specified file extensions.
Configure a custom HTTP response header Allows you to customize HTTP response headers for expired resources.
Customize an error page Allows you to customize an error page for a specific HTTP status code.
Create a URI rewrite rule Allows you to redirect request URIs to the specified URIs by using 302 redirects.