What other changes have you made to DNS? From reading your post, I am of the opinion you think that merely changing DNS to dynamic will make all your changes for you. Is this the case?
All Dynamic DNS does is Dynamically register client IP addresses as they are reported by the client. Dynamic DNS does not magically reconfigure the DNS configuration of your DNS server, nor does it change the IP settings on clients.
Are client IP addresses dynamicaly assigned or are they static? If dynamically assigned, were DHCP scope settings changed to take into account the new IP address block as well as the new IP address of the domain controllers?
If the client IP addresses ar static, how were client addresses changed? Were they pointed to the NEW IP address of the DNS server? Clients can't register their new IP addresses if they don't know the new IP address of the DNS server.
In DNS, did you update all the name server records to take into account the new IP address of the DNS server(s)? Does the DNS server point to itself for Primary DNS