# Troubleshooting HTTP validation problems
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Consult the following guidance if you're having trouble validating a certificate with HTTP.

The first step in HTTP troubleshooting is to check the current status of your domain with tools such as the following:
+ **curl** — [Linux and Windows](https://curl.se/docs/manpage.html)
+ **wget** — [Linux and Windows](https://www.gnu.org/software/wget/manual/wget.html)

**Topics**
+ [Content mismatch between RedirectFrom and RedirectTo locations](#http-validation-content-mismatch)
+ [Incorrect CloudFront configuration](#http-validation-cloudfront-configuration)
+ [HTTP redirect issues](http-validation-redirect-issues.md)
+ [Validation timeout](http-validation-timeout.md)

## Content mismatch between RedirectFrom and RedirectTo locations
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If the content at the `RedirectFrom` location doesn't match the content at the `RedirectTo` location, validation will fail. Ensure that the content is identical for each domain in the certificate.

## Incorrect CloudFront configuration
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Make sure your CloudFront distribution is correctly configured to serve the validation content. Check that the origin and behavior settings are correct and that the distribution is deployed.