AutodiscoverServiceInternalUri is the the internal URL of the Autodiscover service.
Once you specify the internal URL , Domain Joined machines with Outlook will look at the AutodiscoverInternalURi acting as a Service Connection Point.
While Outlook trying to connect with different Autodiscover methods , Service Connection Point stands first. In some cases even after migrating to a hosting provider or to Office 365 we can see outlook still looking at the local exchange server and not to the right exchange server, Most of the cases as internal autodiscover is specified , Outlook takes the internal url as a priority.
Get-ClientAccessServer | fl AutodiscoverService*
To set the url
Set-ClientAccessServer "CasServerName" –AutoDiscoverServiceInternalUri "https://autodiscover.careexchange.in/Autodiscover/Autodiscover.xml"
Running Test E-Mail AutoConfiguration