Yep in fact it's the kind of think provided by ultradns that I need I think.
My mind start to be messed up with the DNS thing... I'll try to explain a new time my problem.
I've a reseller web space account and a directi reseller account.
My website as one IP for www.luhost.com
and 2 others, for ns1.luhost.com and ns2.luhost.com
I realized that those 3 IPs are one the same server, which is totally dumb in my opinion. That's why I want to change my ns, to have 4 of them in different location.
I want them to looks like ns1.luhost.com etc and not ns1.blablabla.com, etc...
If I understood well what you told before,
Let's say I sign up to dnsmadeeasy.com to obtain use their managed NS service to have a good redundancy of ns (http://www.dnsmadeeasy.com/s0306/aboutus/net.html
but they will provide me with ns like: ns1.dnsmadeasy.com etc...
Consequently, I just have to use the option in directi to create child ns, to point ns1.luhost.com to ns1.dnsmadeeasy.com etc...
And then nobody will know, that I am using the dnsmadeeasy ns?
Am I correct or did I completly miss something???