ispconfig and dns. 2 questions. DNS guru wanted

[chachdog]

1) If am using this linux box to do dns for sites not residing on the box. ie web sites sitting on another server. what information goes into the soa record ip address field when creating the dns records? Do i enter the authoratative dns server listed at the registrar or the linux dns ip address or the ip address of the server where the site is residing?

2) The next tab. the options tab. what information goes into the name server 1 & 2 boxes? is it the linux dns ip or the authoratative dns server listed at the registrar?

note:
This box is not the authoratative server for any of the domains housed on this box. We have our authoratative server configured with slave records to pull information from the master linux dns.

it goes like this.
registrar says pull from ns1.example.com. ns1 says ok linux has these records and delivers them.

we are trying to cut down on administrative overhead. ns1 in the example is a redundant t1 device. it has to be part of the dns for the redundancy part to work right.