Exchange 2010 CAS array and EWS


  • We currently have a 2010 CAS array between two AD sites.  There is also a DAG that reaches across these two sites.  We have some Mac users that are using Outlook 2011 which uses EWS.  Those users get inconsistent results when they try to attach to mail servers.  I did not setup the CAS array, so I can't attest to whether it is set up correctly or not.  Because the CAS array does not use any form of NLB, I am not sure on how the Internal and External URL's should be setup.

    When I look at how EWS is currently setup, it looks wrong, but I am not sure.  Here is how it is currently setup:

    server adsite1-cas001

    internal url:

    external url:

    server adsite2-cas001

    internal url:

    external url:

    both external urls go to the public facing ip for both of those servers.

    Any ideas or suggestions would be greatly appreciated.



    Tuesday, April 23, 2013 6:38 PM

All replies

  • Hi,

    First we should not have single cas array for two different site. each site should have a dedicated cas array.
    even if you have single cas server in a site, it is good to have cas array created, and add that single cas server to the array.

    if you are using cas array then the url should be:

    internal url:

    external url: https://external domain/ews/exchange.asmx

    for your site2:

    is this site a internet facing??

    if yes then:

    internal url:

    external url: https://external url/ews/exchange.asmx

    if it is non-internet facing site then:

    internal url:

    external url: $null

    If you are not using cas-array then you can use the FQDN of the cas server.



    Wednesday, April 24, 2013 7:17 AM
  • Viman,

    Thank you for your response.  The second AD site's cas array is public facing and we have external DNS for setup.  So it seems that our setup IS as you suggested.  Yet, when our Outlook 2011 users are off network, they can't connect.  When I look at the settings on their Outlook, it is showing the internal URL, which explains why it isn't working.  I reset it to the external url,  and it works for a time and then reverts back to the internal url.  

    Any thoughts?

    Thanks for your assistance so far!

    Wednesday, April 24, 2013 10:20 AM
  • Hi,

    When you create the CAS array after the mailbox database is created, please make sure you run the Set-MailboxDatabase to assign the value of RpcClientAccessServer with the FQDN of CAS array.

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    Sean Xiao
    TechNet Community Support

    Monday, May 06, 2013 6:20 AM