Systems on network can not contact domain controller

Please help. i can't join systems to the domain again (windows server 2003), printers shared are no more responding to printing request except if connected directly. Error message while trying to join to domain says "Host (A) records that map the name of the AD domain controller to its IP ady are missing OR contain incorrect addresses. OR AD CS registered in DNS are not connected to the network or are not running.

I have check all configurations and all seems to be ok. PLEASE HELP URGENTLY.Thanks.