DHCP+DNS

http://mxtoolbox.com/SuperTool.aspx?action=mx%3apeer.st&run=toolpage
Google Public DNS
DHCP Server
How To Set Up Linux DNS Services
BIND 

dig +trace +additional -t A peer.st.

Keine IP-Adressen frei

tail -f /var/log/messages
vi /var/lib/dhcp/db/dhcpd.leases
rm /var/lib/dhcp/db/dhcpd.leases
/etc/init.d/dhcpd restart