subdomain handling (own DNS and two different ISPs)

[Kevin Darcy]

Michelle Konzack wrote:
> Hmmm wierd...  I was thinking I am unsubscribed again from those list...
> Gotten no messages since 2008-09-10 and  now  I  have  gotten  over  450
> messages at once from the list...  Was there a List-Server Problem?
> Am 2008-09-22 14:38:47, schrieb Matus UHLAR - fantomas:
>   
>> is that really tamay-dogan.net?
>>     
>
> Yes and my provisory domain is currently Hosted in by my german provider
> "Vallendor EDV Service" at  Hetzner  in  Nürnberg.  My  new  website  is
> already in course and is running very fine (with some  small  exceptions
> not related to DNS)
>
> My current problem is, that my current german hoster create singel zones
> for  example  <tamay-dogan.net>  and  there  are  NO   subdomains   like
> <debian.tamay-dogan.net>. Instead the hosts are 
>
> www.debian         IN A <IP>
> consultants.debian IN CNAME www.debian
>
> which simplyfy the administration @ISP but in my eyes it is  crap  since
> it let me run into grave problems for my intranet which has <private> as
> subdomain and since IF I am offline, all is working fine, but one time I
> go online over GSM for example, /etc/resolv.conf is updated and...
>
> ...a request to <samba3.private.tamay-dogan.net> (my NFS mounted  /home)
> goes now to the DNS server of my ISP  and  does  not  stay  @home.  More
> stress produce <mail.private.tamay-dogan.net> which should  only  handel
> mails for the LOCAL-NET <private>.  Grmpf!
>
> Since I can not update the whole network at once,  I  need  a  provisory
> solution for it...
>   
I think the general solution to this problem is to run your own local 
nameserver instance, hosting your own private zone(s), and then make use 
of hooks in the connect/disconnect scripts/routines in order to switch 
your nameserver configuration around, for resolution of everything else. 
The ISC DHCP client supports this kind of customization "hook" within 
dhclient-script (although I've never actually used that facility). When 
you're disconnected, your DNS would be self-contained; when you're 
connected, in addition to being able to resolve private names, it would 
also have the ability to resolve Internet names, either through 
forwarding, iterative resolution, or some other means. /etc/resolv.conf 
would be pointed to your own local nameserver instance regardless of 
whether you're connected to the Internet or not.

                                                                         
                  - Kevin