I only read old posts about powerdns im running powerdns outside ispconfig for several years. IS there a way to sync powerdns and ispconfig. The idee is that powerdns can be managed from 2 places (not all domains are in ispconfig)
You could run bind on the ispconfig server and pull zone transfers from powerdns. Or ISPConfig has an API, you could try walking through the dns info via that and building up the config files you need. There's also a 'plugin' interface where you could write a server-side plugin that reacts to the right events (not sure if my terminology is right there), eg. a client adds a DNS domain, your plugin gets called and triggers your remote powerdns server to add records or setup a zone transfer.