NAS share not accessible using a CNAME from Windows 2008 R2

I have a NAS filer share say \xyz.abc.def.com. I am trying to access the share from Windows server 2008R2 Server.

We have a CNAME xyz.def.com pointing to xyz.abc.def.com.

I am able to access the share using \xyz.abc.def.com as well as the IP but unable to access the share using \xyz.def.com

a) DisableStrictNameChecking is 1 on Windows Server 2008R2 b) NetBios over TCP is default. I tried setting it to Enabled but no luck

I get the error 0x80004005, unspecified error

Have you checked the basics and verified that DNS is resolving the CNAME properly? Use nslookup from the machine in question (to ensure that it can resolve the address, as knowing a different system can resolve it would not be helpful) and lookup the records.