What is secure DNS?

can someone give a detailed explanation of what Secure DNS is and how it works? I did not tick that option during install. If I want to add this feature will I have to re install? Or can I turn this feature on?

I have no idea what it is but if you go to remove or upgrade in start menu - comodo - cis. You can add/remove cis features without a clean install, just a reboot is needed.

It’s just a replacement set of DNS lookup servers run by Comodo (secure & fast ones). CIS’ Help gives full details & how to manually apply it if you upgraded (both XP & Vista).