# Purge and Prefetch

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

Marks resources that are cached on all points of presence (POPs) as expired. When a POP receives a request, the POP redirects the request to the origin server to retrieve the requested resource. Then, the resource is returned to the client and cached on the POP. The refresh feature reduces the cache hit ratio.

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

Prefetches resources from the origin server and caches the resources on POPs. When a POP receives a request, the POP directly returns the requested resource to the client because the resource is already cached on the POP. The prefetch feature increases the cache hit ratio.

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

<mark style="color:blue;">Only users with full access can add new domain. Regarding how to set permissions, see</mark> [<mark style="color:purple;">User and Permissions</mark>](/welcome/content-delivery-network/user-and-permissions.md)<mark style="color:blue;">.</mark>
{% endhint %}


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