Part 1 of our Series introduced the Service Connection Point. Now when Outlook tries to reach the SCP it will get a response with a Servername and an URL (you remember?)
Outlook now tries to reach that URL because it is interested to get the information provided within the XML. The response of Autodiscover from an Exchange 2016 Server after a default installation will look like this:
Here we can see a lot of information. Let’s break down the information to a few less and readable segments – for instance the protocol types EXCH and EXPR
The different type of protocols define the configuration to know if the connection is meant ‘internal’ or ‘external’
EXCH is the internal configuration
EXPR is the external configuration
The definition ‘internal’ or ‘external’ does not always mean the connection will be outside your network or inside. It depends on what DNS is getting back to your client when we try to reach for example our OWA URL https://webmail.domain.local/owa/
Outlook first tries to reach the internal URL. If this is sucessful the internal URLs will be used. If not – no response for example than the external URL will be used.
When Outlook was able to figure out on which URLs Exchange can be reached it tries to open that connection.
So keep one very important thing in your mind: Autodiscover is simple the process to send an XML file to Outlook so that it does know where it should connect. Not more or less.
Your EXGuru – aka Peter Forster – aka Satschent Peter