Hi,

I'm looking for a redundant solution with Exchange 2010.

Here is the design :

AD Site A
CASHUB01 (CAS and HUB roles)
MAILBOX01 (Mailbox role)

AD Site B
CASHUB02 (CAS and HUB roles)
MAILBOX02 (Mailbox role)

A DAG is configure with servers MAILBOX01 and MAILBOX02.
A NLB CAS Array is configure between servers CASHUB01 and CASHUB02. 

When users connect to CASHUB02 with outlook, it prompts for password.
Is it because CASHUB02 is not in the same AD Site as CASHUB01?
If yes, how can i correct this?

Hi ,

Cas array in exchange 2010 could not be extended between the active directory sites.So you need to create a separate cas array for each active directory site and check the results .

Reference link :

http://blogs.technet.com/b/exchange/archive/2012/03/23/demystifying-the-cas-array-object-part-1.aspx

Note : By the way you need to have the separate NLB clusters for each site.

Ok, so if I want a NLB, I must have 2 CAS in the same AD site, right?

So if we design it like this :

AD Site A
CASHUB01 (CAS and HUB roles)
CASHUB02 (CAS and HUB roles)
MAILBOX01 (Mailbox role)

AD Site B
MAILBOX02 (Mailbox role)

A DAG is configure with servers MAILBOX01 and MAILBOX02.
A NLB CAS Array is configure between servers CASHUB01 and CASHUB02. 

Does it works?

Hi ,

On the above configuration if the entire primary site is down then the clients cannot able to connect to the exchange server because all the connectivity in exchange 2010 will go via cas servers expect the public folder connectivity.So each ad site must contain single mbx ,cas and the domain controller.

Step 1 : Just create a CAS array object in each site and also create the host A record for the each cas array name and it should point to the respective NLB cluster IP address.

I mean cas array in site A should point to the ip address of the NLB cluster in site A and cas array name in site B should point to the ip address of the NLB cluster in site B.

Step 2 : Then create a NLB cluster in site A with the below mentioned cas servers for redundancy 

CASHUB01 (CAS and hub roles)
CASHUB02 (CAS and hub roles )

Step 3: Then create the a NLB cluster in site B with the below mentioned cas server for redundancy.

CASHUB03 (CAS and HUB roles)
CASHUB04 (CAS and hub roles)