[Samba] Samba4 multiple DC architecture

[Julien TEHERY]

Hello


I actually have two Samba4 DCs on a main production site.
We have several remote sites where users authenticate on our main DCs 
through VPNs.

We would like to add an additional DC per site.
Do we have to set something particular or do we have to simply add an 
additional samba4 server per site with

samba-tool domain join mondomaine.lan DC -U administrator --realm=MYDOMAIN.LAN -W MYDOMAIN



For information we have almost 100 sites, that means  potentially 100 
secondary DCs.
Is it possible or is there a limit that samba4 can support in terms of 
number of replicated DC's ?

I guess the best way is to use Active Directory sites feature.
https://wiki.samba.org/index.php/Active_Directory_Sites

One last question about provisionning secondary DC (with or whitout site 
options), is it mandatory to specify the dns-backend option ?
For example if the master has been provisionned with BIND9_DLZ backend, 
do I have to specify it during the join of a remote DC ?


Regards,

Julien