Quoting Stephen Rothwell on Friday October 04, 2002:
| 
| There is no technical need to tell the registry if the name servers
| are not in the domain.  The only thing the parent NS needs to know
| in this case is the NAME of the name servers (because they can be looked
| up using the DNS).

Depends on the glue policy of the registry. Naturally if the name
servers are inside the delegated zone it must have glue, or in the case
of a Verisign zone, it puts glue on everything. So.. if there is glue,
you have to tell the registry. 

kim