Each database is by default associated with a Client Access server and the association of a database with an array of Client Access servers must be done manually by the administrator.

To create the Internal DNS Entry:

On your DNS server, create a new DNS entry for the new array:

1.On the DNS Manager, create a New Host (A) for your domain.

2.The name must be unique and not a machine name.

3.Enter the IP address for the array, which also must be unique.


Name: CAS-Array

FQDN: CAS-Array.contoso.com

IP address:

The next step is to set up a Network Load Balancing, which can be a Hardware NLB or Windows Load Balancing. To install the Windows Network Balancing for Windows 2008, follow the Microsoft TechNet articles:

Installing Network Load Balancing


Create a New Network Load Balancing Cluster


When configure the load balancing array, set to load balance the MAPI RPC ports:


·RPC (1024-65535 UDP/TCP)

·HTTP (80/443 TCP)

To create the Client Access server array

There can be only one CAS array in each Active Directory site. To create the array in Active Directory:

1.Run the follow cmdlet to create the new CAS array:

New-ClientAccessArray -fqdn <FQDN_of_array> -site <SiteName>

The FQDN_of_array is the FQDN created on the DNS entry.


New-ClientAccessArray –Fqdn CAS-Array.contoso.com –Site NY

Any new created mailbox database will be automatically associated with this array, and for the exiting mailbox databases, set the new CAS array:

Set-MailboxDatabase <MailboxDatabaseName> –RpcClientAccessServer <Casarray>


Set-MailboxDatabase “Mailbox Database 1898676755” –RpcClientAccessServer CAS-Array.contoso.com

To set for multiple databases:

Get-MailboxDatabase | Set-MailboxDatabase –RpcClientAccessServer CAS-Array.contoso.com