Features

With caching features, you can configure the cache time-to-live (TTL), status code expiration time, HTTP response headers, custom error pages, custom redirects, custom cache keys, and cross-origin resource sharing (CORS). You can flexibly configure each of these features to meet diverse business requirements in different scenarios.

Feature	Description
Cache TTL	Cache TTL specifies the time period after which an origin server resource cached on CDN points of presence (POPs) expires. After the preset TTL ends, CDN POPs label the corresponding resource cache as expired. You can configure the cache TTL for a static resource based on your business requirements by specifying a path or filename extension.
Cache TTL for HTTP status code	When CDN POPs obtain resources from an origin server, the origin server returns response status codes. In the eSurfing Cloud CDN console, you can configure expiration time for error status codes such as 4XX and 5XX. If a client requests the same resource again before the expiration time you configure, CDN directly returns the cached status code instead of sending the request to the origin server. This reduces the workload on the origin server.
Cache TTL for HTTP status code (honor origin version)	When the origin responds with a special http status code with relevant cache headers, the special http status code caching rule will honor the relevant cache headers given by the origin. The cache TTL set by the CDN will only take effect when there is no relevant cache headers from origin.
HTTP Response Headers	HTTP response headers are a component of the header section in HTTP response messages. HTTP response headers carry and bring specific response header values to clients. You can configure custom HTTP response headers in the CDN console. When your user requests resources from an accelerated domain name, CDN carries the configured custom headers in its response messages to implement specific features.
Error page customization	When a page access error occurs, the client shows a default error page, such as 404 Not Found. The default error page is not visually appealing in most cases, resulting in a poor user experience. To improve user experience, CDN POPs can redirect visitors to a custom page when a specified error code appears.
Customized redirection	When a content path on your origin server changes, the corresponding path on CDN POPs changes accordingly. However, the content path in request URLs may not change accordingly. In this case, CDN POPs need to use the custom redirect feature to rewrite the path so that your user can obtain the requested content.
Cache key settings	A cache key is the unique ID of a cached file on a CDN POP. Each cached file on a CDN POP corresponds to a cache key. You can configure a custom cache key for requests that are sent using different URLs but point to the same file. This helps you increase the cache hit ratio and reduce the number of back-to-origin requests.
CORS settings	CORS is also known as cross-origin access, which is a standard cross-origin solution provided by HTML5. CORS allows web application servers to perform cross-origin access control and ensure secure cross-origin data transmission. When cross-origin resource sharing or access is required in your business, you can configure custom HTTP response headers.

Content Delivery Network

Cache overview