url erro redirect

[matheus21]

how to fix it when you type the wrong URL be directed to index

www.site.com/forum/ddddddddddddddddddddddddddddddd

http://i.imgur.com/Yyv1QSU.png

[Dave]

<a href="https://www.internetearnings.com/how-to-redirect-404-not-found-page-using-htaccess/" target="_blank">https://www.internetearnings.com/how...sing-htaccess/</a>