Issue

• It fails to connect to domain based DFS shares on Windows 2008 R2 servers. It used to work when of the domain controllers were Windows 2003. It is possible to mount directly to the backend DFS server, but not through the Domain Namespace. The smbclient command works to mount share, but mount.cifs is not working.
• It is possible to access share through smbclient command, but mount.cifs fails with below error message:

Here is the output of the first command:
#  mount.cifs \\domain.com\dfs-share /mount/point --verbose -o username=testuser,domain=domainname
Password:
mount.cifs kernel mount options: ip=xx.xx.xx.xx,unc=\\domain.com\dfs-share,,ver=1,user=testuser,domain=domainname,pass=********
Retrying with upper case share name
mount.cifs kernel mount options: ip=xx.xx.xx.xx,unc=\\DOMAIN.COM\DFS-SHARE,,ver=1,user=testuser,domain=domainname,pass=********
mount error(6): No such device or address
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

• CIFS debug shows:

Status code returned 0xc00000cc NT_STATUS_BAD_NETWORK_NAME