![]() In the left-side navigation pane, choose Tools > Refresh and Prefetch. For more information, see Configure 301/302 redirection. If the origin server returns the HTTP 301 or 302 status code and you have enabled 301 or 302 redirection in the DCDN console, the prefetch task is not affected. If the origin server returns a redirection-related status code, such as the HTTP 307 status code, the prefetch task does not follow the redirected address and fails. If you want a prefetch request to include other headers or implement multi-replica prefetch, you can call the PreloadDcdnObjectCaches operation and specify a custom prefetch header by configuring the WithHeader parameter. If cache sharing is configured for a domain name, you can submit a refresh task with the root domain name or any associated domain name to refresh the cache.īy default, prefetch requests include the Accept-Encoding:gzip header. URL refresh, directory refresh, and refresh based on regular expressions support cache sharing. For more information, see Authorize a RAM user to prefetch and refresh resources. If you want to use Resource Access Management (RAM) users to refresh or prefetch resources, you must have the required permissions. A task that has a smaller average file size requires less time to complete. In most cases, most prefetch tasks require 5 to 30 minutes to complete. The period of time required to complete a prefetch task is proportional to the size of the files that you want to prefetch. The origin fetch process consumes more bandwidth resources and the origin server may be overwhelmed. This increases the number of requests that are redirected to the origin server. A large number of prefetch tasks lead to a large number of concurrent download tasks. This means that if the resource you want to refresh has a TTL of less than 5 minutes, you wait for it to expire instead of manually running a refresh task.Īfter you submit and complete a prefetch task, POPs immediately start to retrieve resources from the origin server. This results in high bandwidth costs and more loads on the origin server.Ī refresh task takes effect 5 to 6 minutes after being submitted. If you frequently run refresh tasks, more requests are redirected to the origin server for resources. Then, the resources are returned to the client and cached on POPs. When a POP receives a request for your resources, the request is redirected to the origin server to retrieve the resources. ![]() This accelerates content delivery and reduces loads on the origin server when a large number of visitors want to access your resources.Īfter you submit and complete a refresh task, your resources that are cached on POPs are removed. After the product is launched, visitors can download the package from POPs. This accelerates content delivery.īefore you release an installation or upgrade package of a product, you can prefetch the package to POPs. After the event starts, visitors can access the static resources that are already cached on POPs. If you want to hold a major event, you can prefetch the static resources of the event page to POPs. This way, the resources are deleted from the POPs. ![]() In this case, you need to use the refresh feature to update the DCDN cache. This ensures that visitors can retrieve up-to-date resources from POPs.ĭelete resources that violate the limits of DCDNĪfter you delete resources that violate the terms that are described in Before you start from your origin server, visitors can still access the resources because the resources are cached on points of presence (POPs). ![]() Then, DCDN refreshes the resources that are cached on POPs. The following table describes the common scenarios in which the refresh or prefetch feature is used.Īfter resources on your origin server are updated, you can submit the URLs or the directories of the updated resources.
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