To check winbind functionality, you have try:
wbinfo -u
getent passwd
What is the next action?

A.
The contents of smb.conf should be verified

B.
The contents of resolv.conf should be verified

C.
The contents of nsswitch.conf should be verified

D.
The contents of winbind.conf should be verified

E.
The contents of lmhosts should be verified