You have to remove the domain name when doing an internal redirect. For example:

User URL: yoursite.com/products/my-great-product.html
URL of the script: yoursite.com/showproduct.php?name=my-great-product
Redirect Rule: RewriteRule ^/products/(.*).html$ /showproduct.php?name=$1 [L]

Otherwise, if you include the domain name in the redirect rule, the server will assume you want to redirect the user to an external site and will use a 302 redirect.

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