DNSSEC domain and sub-domains

[rod at iastate.edu]

We are getting ready to implement DNSSEC on our campus. Our main domain is iastate.edu. I have zone records for department and units, such as admin.iastate.edu, its.iastate.edu, cs.iastate.edu and ee.iastate.edu. Two of the zones are delegated (cs.iastate.edu and ee.iastate.edu). If we implement DNSSEC for iastate.edu, admin.iastate.edu and its.iastate.edu, must DNSSEC be implemented for the delegated zones as well?

-- 
Rod Eldridge
Network Infrastructure, Authentication, & Directory Services Team
Mac OS X Development Team
IT Services, Iowa State University of Science and Technology