Exchange 2010 two datacenters two CAS array

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Hello all

We are planning on configuring Exchange 2010 with a single DAG that spans two seperate AD and physical sites (AD site1, AD site2). The DAG will contain 4 mailbox servers, and there will be active databases in each datacenter\ADsite. We will also configure two cas array's (one per AD site) The AD sites that contain the Exchange 2010 servers will not contain any client workstations (they are all in seperate AD sites) If a user who is in AD site 3 lauches outlook 2010, and the users mailbox is located in AD site1, then will the CAS servers that are also located in AD site1 service the request from the outlook client?

If the mailbox is located in AD site 2 but the CAS servers located in AD site1 service the request from the client, will these CAS servers then proxy the request to the CAS servers located in AD site2?

and lastly

If all users access outlook anywhere EAS,OWA from a sigle location (meaning only the CAS servers located in AD site 1 are internet accessible, then do i need to have the same SAN cert on the cas servers in AD site2? In the event i lose the cas array in AD site 1, i need to failover all the exchange web services to the CAS servers in AD site 2. Also when i configure my cert for do i need to include the name of the CAS array in the cert?

Bulls on Parade

ibenna [MVP]

I would like to understand why the Exchange servers are being placed in their own AD sites please. Can you elaborate? From my understanding of your configuration, this is what I beleive will happen (anyone, please correct me if I am wrong!):

When you configure the CAS array in ADSite1, you will configure the mailbox databases located on the mailbox server in ADSite1 to use this CAS Array (lets call it Array1). When you configure your client to connect to their mailbox from ADSite3, Exchange will locate the user's mailbox in ADSite1 and will automatically configure the Outlook profile to use Array1 to service the client. Whenever this client opens Outlook, they will be connected to a CAS server that is a member of Array1.

For your second question, If the client is configured to connect to Array2 in ADSite2 but their mailbox is located on a server in ADSite1, then there will be a proxy request sent to Array1 by Array2.

Regardless of where the users will be connecting from (internal or extrernal), you will still require the names of Array1 and Array2 on the certificates so that internal clients will not be getting the security certificate warning!

Thank you, Ibrahim Benna MCSA+Messaging, MCSE+Messaging, MCT, MVP " Did you backup your Information Store Today?!"


The Exchange servers are located in two seperate datacenters, the clients will be spread across 5 different AD sites.Bulls on Parade

Jonas Andersson [MCITP]

I agree with you Ibrahim
With the method above there will be a manual step to point the DB's to the other CAS Array in ADsite2

Jonas Andersson MCTS: Microsoft Exchange Server 2007/2010 | MCITP: EMA 2007/2010 | MCSE/MCSA Blog:

Michel de Rooij

1) Client will be served by CAS servers residing in the same site where their mailbox is located;

2) See #1. CAS proxying will only occur between internet-facing and non-internet-facing CAS servers.

More info on CAS redirection and proxying:

3) For your convenience, why not use SAN cert with - besides the external URLs etc - all CAS array names etc. Ofcourse, internally self-signed certs can be used for domain-joined clients.

Michel de Rooij,
MCITP Ent.Msg 2007+2010| MCTS W2008, Ex2007+2010 Conf, OCS2007 Conf | MCSE+Msg2k3 | MCSE+Inet2k3 | Prince2 Fnd | ITIL
I blog on and tweet on
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