add an ip as name server.

[tristezo2k]

Hello.
when I first installed ispCP, I had just one ip1, and an external DNS server.
Now I'd like to use it as dns server too.
I added ip2 at the OS starting script (debian 6.0.1) so now I have at eth0 and eth0:1 ip1 and ip2 [*1]
I noticed ispCP knows that new ip2 since I see it at
/admin/ip_manage.php
However, when I dig a domain I receive ns1 and ns1 both pointing to ip1 instead ns1 at ip1 and ns2 to ip2
How can I fix this?

*1: is this the correct action to add an IP to ispCP? or should I use the control panel to add it?
Will ispCP modify the OS starting script?

Thanks in advance.
Sebastian