> For the complete documentation index, see [llms.txt](https://gitbook.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gitbook.com/docs/developers/gitbook-api/api-reference/custom-hostnames/revalidate-a-custom-hostname-dns.md).

# Revalidate a custom hostname DNS

Revalidate DNS records and status.

```json
{"openapi":"3.1.0","info":{"title":"GitBook API","version":"0.0.1-beta"},"tags":[{"name":"custom-hostnames","description":"Extend your brand identity by mapping personalized domain names to your docs. This can help unify your documentation site with your existing company properties.\n\n{% openapi-schemas spec=\"gitbook\" schemas=\"CustomHostname\" grouped=\"false\" %}\n    The CustomHostname object\n{% endopenapi-schemas %}\n"}],"servers":[{"url":"{host}/v1","variables":{"host":{"default":"https://api.gitbook.com"}}}],"security":[{"user-internal":[]}],"components":{"securitySchemes":{"user-internal":{"type":"http","scheme":"bearer"}},"parameters":{"hostname":{"name":"hostname","in":"path","required":true,"description":"The custom hostname, for example \"docs.gitbook.com\"","schema":{"type":"string"}}},"responses":{"ConflictError":{"description":"Conflict","content":{"application/json":{"schema":{"type":"object","required":["error"],"properties":{"error":{"type":"object","properties":{"code":{"type":"integer","format":"int32","enum":[409]},"message":{"type":"string"}},"required":["code","message"]}}}}}}}},"paths":{"/custom-hostnames/{hostname}":{"patch":{"operationId":"dnsRevalidateCustomHostname","summary":"Revalidate a custom hostname DNS","description":"Revalidate DNS records and status.","tags":["custom-hostnames"],"parameters":[{"$ref":"#/components/parameters/hostname"}],"responses":{"204":{"description":"DNS validation has been retriggered"},"400":{"description":"The current custom hostname is inactive and cannot be revalidated","$ref":"#/components/responses/ConflictError"},"409":{"description":"The current custom hostname status does not allow DNS revalidation","$ref":"#/components/responses/ConflictError"}}}}}}
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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://gitbook.com/docs/developers/gitbook-api/api-reference/custom-hostnames/revalidate-a-custom-hostname-dns.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.