RHELではMIT Kerberosを利用しておりますが、これとsamba のバージョン4でADドメインコントローラ機能を実装するために独自に実装されたHeimdalが競合するため、そもそもドメインコントローラ機能を同梱しておりません。
以下のドキュメント中にも、sambaでできないこととしてActive Directory のドメインコントローラ機能がございます。
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/ch-File_and_Print_Servers.html#s1-Samba
この同梱されない事情について、Fedoraではsamba-dcパッケージが存在し、以下のように記載がございます。What Samba cannot do:
Act as a BDC for a Windows PDC (and vice versa) Act as an Active Directory domain controller
/usr/share/doc/samba-dc/README.dc
MIT Kerberos 5 Support
=======================
Fedora is using MIT Kerberos implementation as its Kerberos infrastructure of
choice. The Samba build in Fedora is using MIT Kerberos implementation in order
to allow system-wide interoperability between both desktop and server
applications running on the same machine.
At the moment the Samba Active Directory Domain Controller implementation is
not available with MIT Kereberos. FreeIPA and Samba Team members are currently
working on Samba MIT Kerberos support as this is a requirement for a GNU/Linux
distribution integration of Samba AD DC features.
We have just finished migrating the file server and all client utilities to MIT
Kerberos. The result of this work is available in samba-* packages in Fedora.
We'll provide Samba AD DC functionality as soon as its support of MIT Kerberos
KDC will be ready.
In case of further questions do not hesitate to send your inquiries to
samba-owner@fedoraproject.org