Managing DNS is managing primary and secondary zones. When beginning a configuration, it might be better to import the data, especially if you have a large zone. Doing so reduces the chance of error.
If you are using Dynamic DNS (DDNS), when a client receives an address assignment from the DHCP server, a request is made to update eDirectory. The only way to override DDNS is by using the DNS/DHCP Management Utility.
After you have installed and configured your zones, you must still use the DNS/DHCP Management Utility to assign a DNS server to service the zones.