# 刷新和预热

## [刷新](/welcome/cn/content-delivery-network/purge-and-prefetch/purge.md)

标记所有存在点（POPs）上缓存的资源为已过期。当 POP 收到请求时，POP 会将请求重定向到源服务器以检索请求的资源。然后，资源被返回给客户端并缓存在 POP 上。刷新功能降低了缓存命中率。

## [预热](/welcome/cn/content-delivery-network/purge-and-prefetch/prefetch.md)

从源服务器预热资源并将其缓存在 POPs 上。当 POP 收到请求时，POP 会直接将请求的资源返回给客户端，因为该资源已经缓存在 POP 上。预热功能提高了缓存命中率。

{% hint style="info" %} <mark style="color:blue;">**注意**</mark>

<mark style="color:blue;">只有具有完全访问权限的用户才能添加新域名。有关如何设置权限，请参阅</mark> [<mark style="color:purple;">用户和权限</mark>](/welcome/cn/content-delivery-network/user-and-permissions.md)<mark style="color:blue;">。</mark>
{% endhint %}


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