nslcd.conf confguration for Cumulus Linux KB on LDAP Authentication.

nslcd.conf

# /etc/nslcd.conf
# nslcd configuration file. See nslcd.conf(5)
# for details.

# The user and group nslcd should run as.
uid nslcd
gid nslcd

# The location at which the LDAP server(s) should be reachable.
uri ldaps://myadserver.rtp.example.test

# The search base that will be used for all queries.
base ou=support,dc=rtp,dc=example,dc=test

# The LDAP protocol version to use.
#ldap_version 3

# The DN to bind with for normal lookups.
# defconf-set-selections doesn't seem to set this. so have to manually set this.
binddn CN=cumulus admin,CN=Users,DC=rtp,DC=example,DC=test
bindpw 1Q2w3e4r!

# The DN used for password modifications by root.
#rootpwmoddn cn=admin,dc=example,dc=com

# SSL options
#ssl off (default)
# Not good does not prevent man in the middle attacks
#tls_reqcert demand(default)
tls_cacertfile /etc/ssl/certs/rtp-example-ca.crt

# The search scope.
#scope sub

# Add nested group support
# Supported in nslcd 0.9 and higher.
# default wheezy install of nslcd supports on 0.8. wheezy-backports has 0.9
nss_nested_groups yes

# Mappings for Active Directory
# (replace the SIDs in the objectSid mappings with the value for your domain)
# "dsquery * -filter (samaccountname=testuser1) -attr ObjectSID" where cn == 'testuser1'
pagesize 1000
referrals off
idle_timelimit 1000

# Do not allow uids lower than 100 to login (aka Administrator)
# not needed as pam already has this support
# nss_min_uid 1000

# This filter says to get all users who are part of the cumuluslnxadm group. Supports nested groups.
# Example, mary is part of the snrnetworkadm group which is part of cumuluslnxadm group
# Ref: http://msdn.microsoft.com/en-us/library/aa746475%28VS.85%29.aspx (LDAP_MATCHING_RULE_IN_CHAIN)
filter passwd (&(Objectclass=user)(!(objectClass=computer))(memberOf:1.2.840.113556.1.4.1941:=cn=cumuluslnxadm,ou=groups,ou=support,dc=rtp,dc=example,dc=test))
map    passwd uid           sAMAccountName
map    passwd uidNumber     objectSid:S-1-5-21-1391733952-3059161487-1245441232
map    passwd gidNumber     objectSid:S-1-5-21-1391733952-3059161487-1245441232
map    passwd homeDirectory "/home/$sAMAccountName"
map    passwd gecos         displayName
map    passwd loginShell    "/bin/bash"

# Filter for any AD group or user in the baseDN. the reason for filtering for the
# user to make sure group listing for user files don't say '<user> <gid>'. instead will say '<user> <user>'
# So for cosmetic reasons..nothing more.
filter group (&(|(objectClass=group)(Objectclass=user))(!(objectClass=computer)))
map    group gidNumber     objectSid:S-1-5-21-1391733952-3059161487-1245441232
map    group cn            sAMAccountName

Hah! at least it works now:
The specified S-1-5-21-... must be the objectSid of the domain!
(The question why this works still remains)