I recently faced a problem whereby I had to install a Windows 2008 R2 Failover Cluster Server and make a CNAME alias point to it but I was unable to get to the CNAME network share from remote clients.
Fortunately this wasn't a difficult problem to solve as I was aware of the existence of the DisableStrictNameChecking registry key under previous Windows versions. This key tells the server to allow inbound connections which are not explicitly directed to its main hostname, so it is a protective feature, not a bug.
So, to loosen security a bit allowing proper network access to a Windows server using a DNS alias, fire an elevated command prompt, type regedit and move to the following registry key:
Right-click Parameters, click New, and then click DWORD (32-bit) Value.
Type DisableStrictNameChecking and press ENTER.
Double-click the DisableStrictNameChecking registry value and type 1 in the Value data box, click OK and close the Registry Editor.
This should solve your issue with accessing a Windows 2008 R2 server with a CNAME.