I would like to integrate a forest institute.fr (for security raison, I replace real names by mylab and institute)
in this forest, there are many laboratories
my laboratory has no DC so I want use samba4 to have one but we are linked with a neighbourgh laboratory which provide us DHCP and DNS servers

I defined 
administrator@PC50:~$ sudo /usr/local/samba/bin/samba-tool domain provision --use-rfc2307 --interactive
Realm [NEIGHBOURH_LAB.INSTITUTE.FR]: MYLAB.INSTITUTE.FR
 Domain [MYLAB]: 
 Server Role (dc, member, standalone) [dc]: 
 DNS backend (SAMBA_INTERNAL, BIND9_FLATFILE, BIND9_DLZ, NONE) [SAMBA_INTERNAL]: 
 DNS forwarder IP address (write 'none' to disable forwarding) [xxx.xxx.xxx.50]:   note : the delegation of mylab.institute.fr to this IP xxx.xxx.xxx.50 was done 
Administrator password: ........
Retype password: ........
Looking up IPv4 addresses
Looking up IPv6 addresses
No IPv6 address will be assigned
Setting up share.ldb
Setting up secrets.ldb
Setting up the registry
Setting up the privileges database
Setting up idmap db
Setting up SAM db
Setting up sam.ldb partitions and settings
Setting up sam.ldb rootDSE
Pre-loading the Samba 4 and AD schema
Adding DomainDN: DC=mylab,DC=institute,DC=fr
Adding configuration container
Setting up sam.ldb schema
Setting up sam.ldb configuration data
Setting up display specifiers
Modifying display specifiers
Adding users container
Modifying users container
Adding computers container
Modifying computers container
Setting up sam.ldb data
Setting up well known security principals
Setting up sam.ldb users and groups
Setting up self join
Adding DNS accounts
Creating CN=MicrosoftDNS,CN=System,DC=mylab,DC=institute,DC=fr
Creating DomainDnsZones and ForestDnsZones partitions
Populating DomainDnsZones and ForestDnsZones partitions
Setting up sam.ldb rootDSE marking as synchronized
Fixing provision GUIDs
A Kerberos configuration suitable for Samba 4 has been generated at /usr/local/samba/private/krb5.conf
Setting up fake yp server settings
Once the above files are installed, your Samba4 server will be ready to use
Server Role:           active directory domain controller
Hostname:              PC50
NetBIOS Domain:        MYLAB
DNS Domain:            mylab.institute.fr
DOMAIN SID:            S-1-5-21-....