When it comes to showing a 404 error page to your visitors, you do not want that generic page to show, and you especially do not want your hosting provider’s ad error page to show either.
In this article, I will show you how to enable the custom 404 error page, for your site.
When you open IIS7 and above, this is pretty much what you will be faced with. Which is way different than previous versions of IIS, and in my opinion, a lot better of a layout, and gives more options to work with, especially when dealing with .NET.
Running Windows Professional Workstations, with IIS installed, you are only allowed to run one website.
However, you can run as many Virtual websites as you want or need.
The virtual site will be accessed like so: localhost/spotlight
(Spotlight being the directory name that was assigned to the one shown in the properties image below).
(To setup IIS on your Windows 7 and above Professional workstation, please view the following article.
Windows 10 IIS10
The first thing that we want to do, is choose the 
] icon in the 
The next page that we are faced with is a list of all available Error pages that you can choose from, to customize.
Double clicking on the 
] error page line, this will open its properties.
The first option is checked by default and set in the 
However, in order to have a custom error page, we will need to point this to a folder located in our website directory.
So we will choose the option 
Execute a URL on this site
] (See image below)
Looking at this page, you can see that we are pointing to the following.
As you can see in the image
As you can see in the image above, we have 2 different Spotlights.
One of them is the reference shortcut (This is what we type in to our web browser to access the website)
The other is the website folder. So you can link to either Of these 2 items, in order to setup the custom 404 error page.
Next we need to set our 
Error Response] we do this by 
Right] clicking on the 404 error message, and choosing
Edit feature Settings]
In the 
Edit Error Pages Settings] page, it is set to 
Detailed errors] by default, however, we want to change it to 
Custom error pages] (or) you can choose the last option if you want to see your errors while designing the site on the production machine, and see the custom error pages while you are on a client machine.
That is it.
It is simple to get your 404 error pages up and running on IIS7 and above.
In this example, I am pointing to a Classic ASP 404 error page, however, you can point to any type of page that you have designed to run under your IIS.
Hope this helps someone, as it is very hard to find any information on this anywhere.
It took me some time to finally figure it out, and get it running on my Windows 10 machine.