[Samba] DC's are unavailable when PDC halted

[Stefan G. Weichinger]

Am 2017-11-08 um 15:03 schrieb L.P.H. van Belle via samba:
> 
> Hai Stefan,
> 
> What happens on the DC itself. 
> The dns `CLIENT queries` (resolving) goes through /etc/resolv.conf 
> And uses these settings. 
> for example, ping www.google.nl from the DC commandline.
> 
> The PC in the lan use the DC DNS but NOT  /etc/resolv.conf of the DC.

Sure, I know.

> That uses the DNS Server settings, internal samba, used the forward setting in smb.conf
> Or bind9_dlz + samba, used the forward setting in bind.
> 
> 
> Now you know this. (DC1)
> /etc/resolv.conf 
> search ADDC.domain.TLD externaldomain.tld
> nameserver IP_OF_DC1 and not localhost/127.0.0.1
> Nameserver IP_of_your_gateway
> Nameserver IP_of_anyother_dns. 
> 
> Now adding a second DC.
> 
> DC1 changes a bit. 
> /etc/resolv.conf 
> search ADDC.domain.TLD externaldomain.tld
> nameserver IP_OF_DC1
> nameserver IP_OF_DC2
> Nameserver IP_of_anyother_dns. 
> 
> DC2.
> /etc/resolv.conf 
> search ADDC.domain.TLD externaldomain.tld
> nameserver IP_OF_DC2
> nameserver IP_OF_DC1
> Nameserver IP_of_anyother_dns. 
> 
> And set you client PC's DNS to the DC.s 
> 
> Results in. 
> 1) if DC1 is down, DC2 is used.
> 2) if DC2 is down, DC1 is used.
> 3) If both DC's are down, the DC still has internet, clients not. 
> But without any DC, your network is in serious problem.. 

that's why I push adding a 2nd ... and the admin there understands ...

> The DC still has internet due to Nameserver IP_of_anyother_dns. 
> And you need that when your in trouble. 

very helpful, thanks!
I think I would have come up with a similar setup, but now I can use
this as *howto* or template ;-)

Stefan