Outlook tries to connect to a dumb CAS Server

Question

Hi team,
I set up a lab environment with a Single Ex server(lets say EX1.domain.com) with both CAS/MBX collocated. No internet, just internal testing. Created mail.domain.com and autodiscover.domain.com and pointed out to EX1 server. All connections are smoothly
going.
Then I decided to add another two CAS servers (EX2, EX3) to the organization and did nothing more than installing, didn't configure array even.
Now, I'm seeing that whenever I disconnect my NIC on EX2 and EX3, some of the clients(Outlook) disconnects and some keeps working. What I'm confused is even after NOT doing anything other than installing, why is my client connecting to the new CAS Server(s)?
Thank you.
Cheers!

Answer 1

You have probably seen this:
http://technet.microsoft.com/en-us/library/bb124251(v=exchg.150).aspx
Using the user credentials, the Outlook 2007, Outlook 2010, or Outlook 2013 client authenticates to Active Directory and searches for the Autodiscover SCP objects. After the client obtains and enumerates the instances of the Autodiscover service, the client
connects to the first Client Access server in the enumerated list and obtains the profile information in the form of XML data that's needed to connect to the user's mailbox and available Exchange features.
Now, for your specific question:
And how does the client select which CAS to connect to in case of a multiple CAS Server entries in
the Autodiscover info, is it a random selection or round-robin etc?
in the instance of multiple CAS that arent in a load balanced array, the domain-joined client enumerates that list and attempts to connect to the oldest CAS ( I.e. the one installed first) and then tries each one in the list after that - usually.  :)
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