NAS share access with alias prompting credential from windows box

Hi All,
Issue: Prompting credential while accessing NAS share via alias on Windows 2003 machine (Cross domain) but able to access on Windows 2008 without credential prompt.
Nature: 
Domain 1 : ABC
Domain 2: XYZ
NAS share on XYZ.
NAS host Name is:  server01.XYZ.com
Alias (CName) created on XYZ is:  cname1.XYZ.com (pointing to Host record server01.XYZ.com)
Accessing NAS share via Alias name on ABC Domain Member servers
     On Windows 2008: accessing via FQDN, CNAME, IP address not asking for credential and able to see the NAS share data. 
     On Windows 2003: accessing via FQDN, IP address not asking for credential and able to see NAS share BUT accessing via cname1.XYZ.com (Alias)          prompting for credential and once we give the credential able to see share.
Requirement: on windows 2003 should not ask for credential.
we have completed below test so far:
1) disable strictnamechecking registry
2) DisableLoopbackCheck registry
3) Backconnectionhostnames  registry
4) set lmcompatibility as NTLM v2 negotiate
any help will be appreciated, thanks in advance.
Regards,  Sadheesh S

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Sincere