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What’s the best approach to enforce HSTS preload for all subdomains?

Asked on Sep 16, 2025

Answer

To enforce HSTS preload for all subdomains, you should include the `preload` directive in your HSTS header and ensure your domain is submitted to the HSTS preload list. This helps browsers automatically enforce HTTPS for your domain and its subdomains.

<!-- BEGIN COPY / PASTE -->
    Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
    <!-- END COPY / PASTE -->

Additional Comment:

Ensure your entire site and all subdomains are served over HTTPS before enabling HSTS with `preload`.
Once preloaded, your domain will be hardcoded into browsers to enforce HTTPS, which cannot be easily reversed.
Regularly check your site's eligibility for the preload list at hstspreload.org.

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Ask any question about Website Security here... and get an instant response.

What’s the best approach to enforce HSTS preload for all subdomains?

Asked on Sep 16, 2025

Answer

Additional Comment:

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