hi all and thanks for all the help!!
i have a vps hosted using a solusVM which is running ispconfig 3 and debian 6.
When i first got it i just set the HOSTNAME as mydomain.com but now ive purchased a small 128mb server which im using as a ns2.mydomain.com which i setup with that hostname and have got it connected successfully to the first server.
What im wanting to know is, what do i need to change so the mydomain.com hostname is ns1.mydomain.com and ensure that postfix ispconfig dns etc still works and the other server can still connect (dont mind reinstalling the ns2 as its just a nameserver if needed)
I followed the setup tutorial here (debian 6 perfect server)
initially then this(roll ya own dns)
when adding my seccond server