Edge Security Acceleration:Overview

Feature

Description

Default cache rules

When you use ESA to accelerate the delivery of static resources on the origin server, ESA caches the resources on the ESA point of presence (POP) that is nearest to the client. Then, you can access and obtain the static resources from the POP instead of the origin server. This prevents origin pulls over a long route and speeds up content delivery. All POPs of ESA are equipped with caching systems. When a user or an origin server interacts with a ESA POP, the caching system caches resources from the origin server and specifies a Time-to-Live (TTL) for the cached resources.

Feature

Description

Development mode

After you enable the development mode, all requests are redirected to the origin server. This allows requests to your website to temporarily bypass the caching components of Edge Security Acceleration (ESA) so that you can verify changes to the cached content. This feature is useful when you want to view changes in real time. Once enabled, the development mode lasts for 3 hours and then is automatically disabled.

Browser cache TTL

The browser cache time-to-live (TTL) is the period of time during which web page resources, such as HTML, CSS, JavaScript files, and images, are stored in the cache of browsers. By default, the TTL follows the Cache-Control header that is configured on the origin server. You can configure the browser cache TTL without modifying the configuration of the origin server. During the TTL, the browser loads the files from the cache for subsequent requests. This speeds up page loading.

Edge cache TTL

The edge cache time-to-live (TTL) is the period of time during which origin resources are cached on Edge Security Acceleration (ESA) points of presence (POPs). When the TTL ends, resources that are cached on POPs are marked as expired. If the requested resource has expired on a POP, the POP retrieves the most recent resource from the origin server and caches it. You can configure a cache TTL for static resources based on file directories or file name extensions.

Query string

When a point of presence (POP) generates a cache key for a request, the POP removes the question mark (?) and query strings that follow the question mark (?), such as user identity and access source, from the request URL. This increases the cache hit ratio and accelerates page loading.

Sort query strings

After you turn on Sort Query Strings, Edge Security Acceleration (ESA) automatically sorts the query strings in the URLs when processing requests. Then, ESA returns the requested resources from the cache or redirects the requests to the origin server based on the sorted query strings. This way, POPs return the same file for requests that contain the same parameters and values, regardless of the order of query strings in the request URLs. This feature improves the cache hit ratio.

Feature

Description

Create cache rules to configure the browser cache TTL

If you want to use different browser cache TTLs in different business scenarios, you can create multiple cache rules and specify different cache policies for the rules.

Create cache rules to configure the POP cache TTL

If you want to use different edge cache TTLs in various business scenarios, you can create multiple cache rules and specify different cache settings in the rules.

Configure a cache TTL for HTTP status codes

When a point of presence (POP) retrieves a resource from the origin server, the origin server returns an HTTP status code. You can configure a cache time-to-live (TTL) for the HTTP status code in the Edge Security Acceleration (ESA) console. When a client requests the same resource, the POP returns the HTTP status code without triggering origin fetch. This reduces loads on the origin server. After a cached HTTP status code expires, requests that trigger the code are redirected to the origin server.

Create custom cache keys

You can create custom cache keys based on different parts of requests, such as the query string, HTTP request headers, or cookies. This way, you can set a cache key for a type of requests that are destined for the same file to prevent the file from being cached as different files. This increases the cache hit ratio and reduces origin requests, response time, and bandwidth usage.

Feature

Description

Purge cache

You can use the purge cache feature to clear cached resources from points of presence (POPs) and retrieve the most recent ones from the origin server. This feature is useful when you update content to or remove illicit content from your origin server. Purging a large number of cached resources in a short period of time results in a significant increase in origin requests, which, in turn, increases loads on the origin server.

Prefetch cache

The prefetch feature of Edge Security Acceleration (ESA) proactively fetches resources from an origin server to points of presence (POPs). This way, ESA can directly serve the resources from the POPs even when the resources are requested for the first time, without the need to retrieve them from the origin server. The prefetch feature increases the cache hit ratio.

Feature

Description

Cache reserve

Edge Security Acceleration (ESA) provides the cache reserve feature to converge origin requests. After you enable the feature, cache reserve points of presence (POPs) serve as top-tier cache for your resources. This allows ESA to retrieve resources from cache reserve POPs, which eliminates unnecessary outbound traffic fees. Cache reserve POPs reserve space for storage. Resources stored on cache reserve POPs are not overwritten by other frequently requested resources.