How do I support 2 primaries?

[George VanDyke]

If I have one web server that needs to have multiple domains
on its virtual interfaces, www.xxx.org and www.xxx.edu.  All
the ip numbers are within a single subnet in a class B
domain.
How can I configure the primary DNS for my original domain
to support additional domain names and be authoritative for
the additional domains.   At least in this case the new
domain we regestered is only one name and one ip number that
was done for an exhibit.

George Van Dyke
vandykeg at si..edu