I have need a secondary dns for my domain registration. And i have yet a secondary dns bij Rollernet.us but our must allow AXFR requests between rollernet server and ours in order for us to get the zone file updates. You may need to add the IP addresses of our name servers to your allowed transfer settings on your name server; Our server will respond to a notify from you to request an update. Although the account manager processes changes in real time, DNS changes may take up to 24 hours to take effect for the rest of the world. But how do did in Bind on Fedora Core 4 with ISPConfig???? Great patrick
You dont have to configure anything in ISPConfig, AXFR with external secondary DNS severs work out of the box.