Need help and advices to make right dns cluster scheme

Hey folks

I need some suggestions to correctly make my dns cluster scheme. Currently i have this following scheme:
http://img17.imageshack.us/img17/6946/currentscheme.jpg

ns3.example.com is Cpanel dedicated web server (shared hosting) and ns4.example.com is dns only (ns3.example.com is synchronized to ns4.example.com ns4's role is stand alone) now i have created new cpanel vps server to host 10~20 sites there standard shared hosting with apache, ftp, mail server etc . . . ,but without a namserver on it, i'm gonna use ns3.example.com and ns4.example com as vps's namservrs like this following figure shows:
http://img576.imageshack.us/img576/7199/scheme2.jpg

I have read the Cpanel's guide to dns clustering and there is written following:

so the question is why i cant link it ? does it provoke dns zone mix up? if i setup Synchronized dns cluster from vps to ns3.example.com and dns role to ns3 will be as stand alone what kind of problem can i face ? If this is not possible, nor recommended what will be the best scheme for me ?
thanks in advance

 

thanks for your suggestion, but i'm not going to have multiple vps with dns only. i have different scheme pleas read it again or see the pictures

I still need help with this . . .