Once a header with HSTS directive is received, a browser will automatically change any insecure requests (http://) to secure (https://)ones, in case a client attempts to establish a further connection with the website. In case of any issues during session establishment, the connection should result in a non-recoverable error.

1. Open “IIS Manager” and select the website you would like to apply HSTS for.
2. Double-click on the “HTTP Response Headers” shortcut:

   

3. Click on “Add” on the right side of “Actions” menu.
4. Enter “Strict-Transport-Security” in the “Name” field
5. Enter “max-age=[time_in_seconds]” in the Value field, for example:

   max-age=31536000

   (31536000 seconds it’s about 1 year)

6. Optionally add “includeSubDomains” in the “Value” field if you would like to apply HSTS policy for subdomains of your domain name, as well as for the main domain name.

   If you would like to include it, “max=age” and “includeSubDomains” directives should be delimited with a semicolon:

   max-age=31536000; includeSubDomains

   

7. Click “Ok”.