Reverse DNS issues

I have been trying to setup an iDM server for several days now... I have the hostnames set correctly for forward dns we will say for example idm.example.com unfortunately the issue is with reverse dns its coming back as idm.attlocal.net. So I changed the dns servers to google which came back with an SBC global as the hostname. I am trying to setup iDM to be the primary domain name server on the network and really dont want to have to setup a domain name server on the network to act as a proxy for reverse dns. Does anyone know of a work around for this issue.