Within your control panel you have the ability to add custom error pages. Custom error pages allows you to define what happens if a browser is looking for a page within your site that is either missing or fails to open for one reason or another.
Adding a Custom 404 error page
The following steps are used to setup a custom error page on a Linux server. If you are needing help regarding a Linux server please visit the article here.
These changes within your Windows server will take effect immediately.