> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/welcome/cn/content-delivery-network/domain-management/cdn-settings/back-to-origin-settings.md).
# 回源设置
设置上游协议，启用 WebSocket，并设置回源主机头。
* 上游协议
* 将上游协议设置为 HTTP：请求将通过你定义的端口重定向到**内网 IP**，使用 HTTP 协议。
* 将上游协议设置为 HTTPS：请求将通过你定义的端口重定向到**公网 IP**，使用 HTTPS 协议。
* WebSocket\
基于 TCP 的协议，适用于需要长时间双向连接的客户端与服务器之间的通信。持久连接通常是实时应用的要求。你可能会在以下场景中使用 WebSocket：社交聊天平台、在线协作工作空间、多人游戏和提供实时数据流的服务（如金融交易平台）。WebSocket 连接中的数据可以双向流动，实现全双工通信。
* 回源主机头\
可以配置不同的回源 HOST 头来访问同一加速域名下的目标源之一。
---
# Agent Instructions
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## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.console.zenlayer.com/welcome/cn/content-delivery-network/domain-management/cdn-settings/back-to-origin-settings.md?ask=&goal=
```
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