Exchange 2007 CCR became one of most popular implementation now specially for customers who seeks redundancy on the level of the database and customer who want to achieve site resiliency without the normal SCC Geo-Cluster requirements. CCR uses the new File Share Witness feature introduced in an update to the Windows 2003 SP1 to act as the witness node instead of implementing a third node in the cluster for that purpose.

Note: We recommend to install the FSW on one of the Hub servers

Also in site resilience implementation we recommend to pre-provision another FSW on the Hub server that is hosted in the backup site and to be used to speed up the process of brining up the backup site in case of disasters, and in order to facilitate such process of brining up the other FSW and as a best practices we recommend to use a CNAME record that is pointing to the server hosting the FSW so in case of disasters you just need to change the CNAME record to point to the other server hosting the standby FSW, easy task. so in general you will create the CNAME record in the DNS that will be pointing to the FSW server.

So where is the problem??? sometimes when you try to use the CNAME record to populate the FSW or even to test the access to the FSW share using the CNAME you will got this error "A duplicate name exists on the network" and you will not be able to proceed. To solve this problem you have to disable the Strict Name Checking, you can do this through registry on the server hosting the FSW:

  1. Start Registry Editor (Regedt32.exe)
  2. Locate and click the following key in the registry

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters

  1. On the Edit menu, click Add Value, and then add the following registry value:

Value name: DisableStrictNameChecking
Data type: REG_DWORD
Radix: Decimal
Value: 1

Note: you have to restart the server after that.