One WordPress website two main domain with IIS

livebillal –
First, did you install WP sub-directory with main domain https://www.one.com?
Second, create a new site called two. Verify that it works by going to https://www.one.com/two.
Third, if you created a directory/folder ‘two’ remove it!
Fourth, configure WP Domain mapping tool for the new ‘two’ site.

You are getting the “Directory Listing Denied” because you created a folder when you should not be.

Now I am clear how multisite works after getting above message.

Also, when I open the https://www.two.com then it shows the message “Directory Listing Denied”

This was wrong. When I add a site, then adding to the site. But It will be shown under “My Sites -> Network Admin” menu at the top. There is showing only https://www.one.com sites. Now I open the https://www.one.com/newsite then it shows below message

The page cannot be found
The page you are looking for might have been removed, had its name changed, or is temporarily unavailable.

Please try the following:

Make sure that the Web site address displayed in the address bar of your browser is spelled and formatted correctly.
If you reached this page by clicking a link, contact the Web site administrator to alert them that the link is incorrectly formatted.
Click the Back button to try another link.

HTTP Error 404 – File or directory not found.
Internet Information Services (IIS)

Technical Information (for support personnel)

Go to Microsoft Product Support Services and perform a title search for the words HTTP and 404.
Open IIS Help, which is accessible in IIS Manager (inetmgr), and search for topics titled Web Site Setup, Common Administrative Tasks, and About Custom Error Messages.

livebillal –
You have a configuration problem. I think I know. If you are using IIS, you should not have .htaccess (though it doesnt hurt). You should be using a web.config. I found through google that people are using this (please verify yourself):

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
            <rule name="wordpress" patternSyntax="Wildcard">
                <match url="*"/>
                    <conditions>
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true"/>
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true"/>
                    </conditions>
                <action type="Rewrite" url="index.php"/>
            </rule></rules>
    </rewrite>
  </system.webServer>
</configuration>

The HTTP error isn’t WordPress.

This was wrong. When I add a site, then adding to the site. But It will be shown under “My Sites -> Network Admin” menu at the top. There is showing only https://www.one.com sites.

THAT is possibly what’s wrong here.

How did you add the site?

Keep in mind, you absolutely have to do everything one step at a time, especially when it’s your first time. Trying to do it all in one go is foolhardy. becuase you don’t know yet how it all works. Heck, I build and rebuild WP daily and I still take time to check each step before moving on. Typos and mistakes happen. It’s totally okay.

site1.com works. Good.

site1.com/newsite does NOT. So before you mess around with mapping you have to fix this ?? One step at a time.

Check your web.config file. We don’t know if you need that or .htaccess because we don’t know your server.

Personally I would switch to Apache instead of IIS. It’s more common and more well known.