<p><strong>What is Cache Expiration Configuration?</strong></p> <p>Cache expiration configuration refers to a set of expiration policies the CDN acceleration nodes should follow when caching your business contents.</p> <p>User resources cached on CDN nodes all have an &quot;Expiration Time&quot;. If a resource cached on a node is not expired, when a user request for the resource reaches the node, the node will directly return the cached resource to the user to speed up the resource acquisition; If a resource is beyond the set validity period and thus becomes expired, the node will forward the user request for the resource to the source station, reacquire and cache the resource, then return it to the user. A reasonable cache validity period can effectively improve the resource hit rate and reduce back-to-source rate, save your bandwidth.</p> <p><strong>How can I adjust the priority of cache configuration?</strong></p> <p>For more information, see Priority Configuration.</p> <p>Can I configure not to cache a specific type of files? Can I set the cache period to &ldquo;0&rdquo; to disable caching?</p> <p>You can configure different cache validity periods for different types of directories and files. If the cache validity period is configured to 0, the CDN node will not cache the resource, in which case the CDN node needs to pull related resources from the source station every time the users send access request to the node.</p> <p><strong>What is the Default Cache Configuration of CDN?</strong></p> <p>Default configuration is as follows when a domain is connected:</p> <p>By default, the cache validity period for all files is 30 days, except general dynamic files (such as .php, .jsp, .asp, .aspx) whose validity period is 0, which means any request for such files will be directly forwarded to the source station.</p> <p>&nbsp;</p> <p><strong>What are Cache Matching Rules?&nbsp; </strong></p> <p>When multiple caching policies are set, the priorities of the entries are determined on a bottom-to-top basis.</p> <p>&nbsp;</p> <p>&bull;&nbsp;&nbsp;&nbsp; <strong>What is cache refresh?</strong></p> <p>Cache refresh includes URL refresh, directory refresh, and URL warm-up. (For more information, see Cache Refresh.)</p> <p>&bull;&nbsp;&nbsp;&nbsp;&nbsp; After you update a resource on the source station, if you want the user to access the updated resource directly, you can use the URL refresh function to refresh the cache on a file-by-file basis.</p> <p>&bull;&nbsp;&nbsp;&nbsp;&nbsp; After you update a resource on the source station, if you want the user to access the updated resource directly, you can also use the directory refresh function to refresh all the files under a directory.</p> <p>&bull;&nbsp;&nbsp;&nbsp;&nbsp; If you want CDN to proactively cache the resource from the source station to the CDN nodes, you can use the URL warm-up function to warm up resources on a file-by-file basis.</p> <p>&nbsp;</p> <p>&bull;&nbsp;&nbsp;&nbsp;&nbsp; Refresh vs. Warm-up:</p> <p>&bull;&nbsp;&nbsp;&nbsp;&nbsp; Once a resource is refreshed, its cache on all the CDN nodes across the entire network will be deleted. When a user requests arrives at a node, the node will pull the corresponding resource from the source station, return it to the user, and cache it to the node to ensure that the user can obtain the latest resource.</p> <p>&bull;&nbsp;&nbsp;&nbsp;&nbsp; When a resource is warmed-up, it will be cached in advance to all the CDN nodes across the entire network. When a user request arrives at a node, the resource can be directly obtained on the node.</p> <p>&nbsp;</p> <p><strong>Will the cached content on CDN cache nodes be updated in real time?</strong></p> <p>No. The cached content on CDN cache nodes are updated based on the cache expiration configuration you set in the console. If you need to update a file&rsquo;s cache in real time, do it by refreshing cache.</p> <p>&nbsp;</p> <p><strong>Is directory refresh supported by CDN?</strong></p> <p>Yes. CDN supports URL refresh, directory refresh, and URL warm-up.</p> <p>&nbsp;</p> <p><strong>Why doesn&rsquo;t directory warm-up or refresh take effect?</strong></p> <p>Please check whether the Last-Modified of the source station has changed; if so, the origin-pull will fail.</p> <p>&nbsp;</p> <p><strong>What is HTTPS?</strong></p> <p>HTTPS (Hypertext Transfer Protocol Secure) is a security protocol built on HTTP protocol to be used for encrypted communication and can effectively ensure data transmission security. When configuring HTTPS, you need to provide the certificate for your domain and deploy it across all CDN nodes on the entire network to achieve encrypted data transmission across the network.</p> <p>&nbsp;</p> <p><strong>Does CDN support HTTPS configuration?</strong></p> <p>Ping An Cloud CDN fully supports HTTPS configuration. You can upload your own certificate for deployment.</p> <p>&nbsp;</p> <p><strong>How can I Configure HTTPS Certificate?</strong></p> <p>You can configure the HTTPS certificate in the CDN Console. For more information, see HTTPS Configuration.</p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p>