It seems like the current implementations of host record is inconsistent at best. I just changed my isp, and since I host my own dns servers, I needed to change the host record for the dns server host name. When I had registered my domain name though networksolutions, they provide a web interface to change host records. Aplus.net doesn't provide a web interface, and I had to send an email their support dept.
It seems like there could be a better way to do this. For each name server listed in the whois record that are subdomains of the domain, the ip address should be looked up from the name servers, that are listed in the whois record, that are in a different domain. Then the registrar could update the host records. This would allow the host records to be updated when ever the zone file for a domain is updated.