This option controls the maximum depth that winbindd will traverse when flattening nested group memberships of Windows domain groups. This is different from the option which implements the Windows NT4 model of local group nesting. The "winbind expand groups" parameter specifically applies to the membership of domain groups. This option also affects the return of non nested group memberships of Windows domain users. With the new default "winbind expand groups = 0" winbind does not query group memberships at all. Be aware that a high value for this parameter can result in system slowdown as the main parent winbindd daemon must perform the group unrolling and will be unable to answer incoming NSS or authentication requests during this time. The default value was changed from 1 to 0 with Samba 4.2. Some broken applications (including some implementations of newgrp and sg) calculate the group memberships of users by traversing groups, such applications will require "winbind expand groups = 1". But the new default makes winbindd more reliable as it doesn't require SAMR access to domain controllers of trusted domains. 0