[Samba] Samba4 with external bind - best practices?

[Rowland penny]

On 26/07/16 09:31, mathias dufresne wrote:
> Hi Elias,
>
> Separating DNS and AD services:
> It should be possible to have AD DNS server hosted on a non-DC server.
> Samba Wiki explain we just have to include
> "/var/lib/samba/private/named.conf" in Bind configuration. This library can
> be replaced be one of those shipped with Bind, this library will need
> configuration for it can deal with remote DC(s).
> Please note I never tried that, 'cause I'm a lazy guy, but that should be
> possible: Bind+DLZ seems to me to be meant for that kind of job.
>
> One (or more) non-DC DNS server dealing with AD DNS servers:
> That is more simple to achieve:
> - just configure AD DNS service as you want (please note that few weeks ago
> Samba's internal DNS server was still not able to work as multi-masters
> which is needed to avoid SPOF in AD, so IMHO the only valid DNS backend is
> bind+DLZ if you want high availability)
> - add a new zone to your existing DNS server (the one which is not AD DC)
> like that one:
> ----------------------------------------------------------------------------------------------
> zone "ad.domain.tld" IN {
>    type forward;
>    forward only;
>    forwarders {
>      <ip of 1st DC>;
>      <ip of 2nd DC>;
>      ....
>      <ip of Nth DC>;
>    };
> };
> ----------------------------------------------------------------------------------------------
> Restart your external non-DC Bind service and it should be able to resolve
> one more zone: the one from your AD.
> What is nice in that is you don't need to take in account _msdcs zone as it
> is a sub zone of "ad.domain.tld", your external Bind will also forward
> requests regarding _msdcs to AD servers.
>
> I did not played with that for a relatively long time and I'm just coming
> back from vacations, so I'm not sure if you would need to allow forwarding
> and recursion on that non-DC DNS server. It could be necessary... Anyway as
> this DNS should be meant to resolve Internet addresses in addition of your
> local domain(s) recursion and forwarding should be accepted already...
>
> Hoping this clarify DNS management a little bit and that helps you,
>
> Mathias
>
>
>

The Samba wiki page: 
https://wiki.samba.org/index.php/Configure_BIND_as_backend_for_Samba_AD

Has these lines:

  * Since the BIND DLZ module accesses the AD database directly, BIND
    for AD zones must be on the same machine.
  * Because the BIND DLZ module uses the information already stored in
    AD, you do not need to create any extra databases.

Or to put it another way, if you want to use bind_dlz, you must run 
Bind9 on the DC and you do not need to create any zones (except the 
reverse zone and you have to do this anyway)

Rowland