Secondary DNS

[joximu]

you can add it to the main domain but you also can add it to a vhost part...

The idea is that ns2 can download a file from ns1 (ispsp) and the part above is the security setting for this.
If you want to use a virtual domain for this transaction (ns1->ns2) you put it in a vhost part otherwise in the main server part...

Hope you see the point - it's up to you :-)

/J