There can be multiple reasons why you cannot join a CIFS server to a domain.
This article describes how to create a CIFS share on the data domain system and how to troubleshoot access to it.
nsrexecd starts as a service under the SYSTEM account which normally does not have the correct security credentials to access the CIFS share.
A short article on how to mount a DFS (distributed file system) on an Oracle Linux 5.11 system.
This article will document how to mount a Windows CIFS file share onto the local file system on the Solaris 11 server.
This is a simplified method taken from the manuls on how to perform the initial configuration on Data Domain system