Domain Name Same As Website Active Directory. We recommend that you use DNS names that are registered with an Internet authority in the Active Directory namespace. Your domain name is included in the URL but a domain is not the same thing as a URL.
By default App Service directs web requests to the root directory of your app code. But certain web frameworks dont start in the root directory. In Windows 2000 and later versions of Windows computers that are members of an Active Directory domain cant have names that are composed completely of numbers.
When using Option 2 or Option 3 it requires a new zone being created highlighted in the image.
Split Horizon allows for the Internal and External name space to be matching. For more information about the NetBIOS name syntax see NetBIOS name syntax. To add a new custom domain name in the left pane click Custom domain names. This caused a problem for users inside the domain trying to reach the external site.