Originally Posted by DOCK
I can't find the field to enter the secondary nameserver for a particular domain.
You can set the defaults under management > server > settings on the dns tab.
The individual nameserver records are all in the DNS-Manager, click on one of the records and you will find the nameserver field on the options tab.
It seems as you look in the wrong area, the dns checkboxes in the isp-manager part are only shortcuts to create dns records, the detailed dns settings and all records are in the dns-manager and not isp-manager.