dhcpd.conf (fix MAC addresses) and changed domain

I realized that a new client (with LAN card from an old client) is getting every time the same IP as the old one had.
A short look at /etc/dhcpd.conf and I found the problem.
There are all IP's in double form. One time with myserver.net and one time with myserver.lan. That happens, because I have changed the hostnames for the domain from myserver.net to myserver.lan some month ago.
I use dhcp leases with fixed MAC's for the Clients in my LAN.

So, the question is now:

How can I build up the dhcpd.conf file with the right config?
I have deleted the entries manual and tried /sbin/e-smith/expand-template /etc/dhcpd.conf again because I made little changes of the lease time for the clients. I was rebuilded with the old myserver.lan and myserver.net config.

At the server-manager every address and IP is displayed ok with myserver.lan settings.
Where are the configurations of the dhcp config from the server-manager are stored?

Can someone give me an advice to get the dhcp work normal only with the myserver.lan addresses and kick the entries of the myserver.net in the dhcpd.conf.

Thanks,

Dominik